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Recursive Factorial Function

Video vocabulary

beforehand

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US / bɪˈfɔ:hænd /

UK / bɪˈfɔ:rhænd /

B2
  • adverb
  • In advance; before a specific event happens

could

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US / kəd /

UK / kʊd /

A1
  • other
  • Past form of 'can' to mean have ability
  • Used to ask for something politely, or to offer

know

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US / nəʊ /

UK / noʊ /

A1
  • verb
  • To be familiar with a person or place, thing
  • To feel sure or be convinced about something
  • To discover or be aware of something
  • To be able to distinguish
  • To have knowledge of things

slightly

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US / ˈslaɪtli /

UK / ˈslaɪtli /

B1
  • adverb
  • Only a little

next

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US / nekst /

UK / nɛkst /

A1
  • adverb
  • The one that follows another in time or order
  • At a time or place directly after the present one
  • noun
  • The one that follows after
  • adjecitve
  • Immediately after the previous one
  • First occurrence after the present one

negative

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US / 'neɡətɪv /

UK / ˈnɛɡətɪv /

A2
  • adjecitve
  • Being harmful, unwanted or unhelpful
  • In mathematics, being less than zero
  • Focusing on the bad aspects; pessimistic
  • noun
  • The opposite to a positive electrical charge
  • In grammar, containing words such as 'no' or 'not'
  • Reply to a question or statement that means 'no'
  • Image on camera film used to make a photo

recursive

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US / rɪˈkɜ:sɪv /

UK / rɪˈkɜ:rsɪv /

A1
  • adjecitve
  • Repeating itself over and over

see

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US / si: /

UK / si /

A1
  • verb
  • To go on a date with someone
  • To predict whether something is, or will be true
  • To understand what someone says
  • To use your eyes to look at something
  • To visit a place often for sightseeing or pleasure
  • To visit or meet with someone
  • To find out by waiting or looking
  • To watch (a game, movie or TV show)

have

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US / həv /

UK / hæv /

A1
  • verb
  • To drink, smoke, eat or use something
  • To experience the effects of something
  • To organize an event, or join in an activity
  • To own, possess, or hold something
  • To cause to happen or produce a particular effect

last

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US / lɑ:st /

UK / læst /

A1
  • adjecitve
  • Most recent; the latest
  • The one before
  • adverb
  • Final; with nothing following; after all others
  • Most recent; the latest
  • determiner
  • The one at the end
  • verb
  • To remain or continue for a certain period of time

part

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US / pɑ:t /

UK / pɑ:rt /

A1
  • adjecitve
  • To some degree; half; not fully
  • noun
  • Division of a book
  • Ratio of something, e.g. 3 of gin, 1 of tonic
  • A line in a person's hair, made with a comb
  • Character an actor plays on stage, movie, or TV
  • Some, but not all of a specific thing
  • Role in causing something to happen
  • verb
  • To make a line in a person's hair, by using a comb
  • To move two things apart creating a space
  • To leave someone, or to break off a relationship

remember

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US / rɪ'membə(r) /

UK / rɪˈmɛmbɚ /

A1
  • verb
  • To give someone a gift, e.g. birthday, wedding
  • To hold a thought in your mind to not forget it
  • To bring a previous image or idea to your mind

exciting

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US / ɪkˈsaɪtɪŋ /

UK / ɪkˈsaɪtɪŋ /

A2
  • adjecitve
  • Creating interest, happiness or pleasurable fear
  • verb
  • To cause a reaction; make active
  • To make someone feel happy, interested or eager

get

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US / ɡet /

UK / ɡɛt /

A1
  • verb
  • To become affected by illness or disease
  • To begin to feel or understand an emotion or idea
  • To send or bring someone or something home, etc.
  • To go somewhere to obtain something
  • To (cause to) do a particular thing
  • To obtain, receive or be given something
  • To currently have
  • To prepare for use
  • To understand something being said or read

gist

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US / dʒɪst /

UK / dʒɪst /

B1
  • noun
  • Main points of something

essentially

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US / ɪˈsenʃəli /

UK / ɪˈsenʃəli /

A2
  • adverb
  • Basically; (said when stating the basic facts)

fascinating

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US / ˈfæsɪneɪtɪŋ /

UK / ˈfæsəˌnetɪŋ /

B1
  • adjecitve
  • Having your attention fixated as though by a spell
  • Very interesting
  • verb
  • To attract or interest greatly

right

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US / raɪt /

UK / raɪt /

A1
  • adjecitve
  • Correct or true
  • The south side of you looking at the rising sun
  • adverb
  • Exactly in a place or time
  • Being appropriate for a particular event
  • In a straight or direct manner
  • noun
  • Something you are legally or morally allowed to do
  • Ideal of what is just and good
  • Political view based on conservatism
  • verb
  • To fix something previously wrong or unjust
  • To make upright, as a boat that has turned over

value

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US / 'vælju: /

UK / ˈvælju /

A1
  • noun
  • Importance you attach to something
  • Some information expressed as a number
  • Stated price of something; worth
  • verb
  • To place a high importance on something
  • To say how much money something is worth

again

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US / ə'ɡen /

UK / əˈɡɛn /

A1
  • adverb
  • One more time, once more

about

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US / ə'baʊt /

UK / əˈbaʊt /

A1
  • adverb
  • To be ready to; going to
  • Nearly; approximately; roughly
  • Near; next to; close to
  • In every direction; in the area of
  • preposition
  • Concerning or of (a topic)

even

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US / 'i:vn /

UK / ˈivən /

A1
  • adjecitve
  • Being equal in influence, power, possibility etc.
  • Being divided equally or fairly
  • (Of teams/contest) with similar chances of success
  • Smooth, level, or regular
  • Can be divided by 2; ending in 2, 4, 6, 8, or 0
  • At a regular, equally steady manner
  • Remaining steady and unchanging
  • adverb
  • (When this is surprising) as well; too
  • (Used to compare two things/stress the difference)
  • verb
  • To make something level; to flatten
  • To make something equal

care

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US / keə(r) /

UK / kɛr /

A1
  • noun
  • Treatment you receive for your health or safety
  • Something that a person worries about
  • verb
  • To feel interest, concern, or worry
  • To look after someone or something

different

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US / ˈdɪfrənt /

UK / ˈdɪfrənt /

A1
  • adjecitve
  • Not of the same kind; unlike other things

label

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US / 'leɪbl /

UK / ˈlebəl /

A2
  • noun
  • A (luxury) brand owned by a company
  • A word or term used to describe a person, thing
  • A piece of paper or material to identify something
  • verb
  • To use a term to describe, often negatively
  • To attach material to identify something

that

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US / ðæt /

UK / ðæt, ðət /

A1
  • adjecitve
  • The person or thing being talked about
  • Used to identify something both the speakers know
  • adverb
  • Used to reinforce adjectives and adverbs
  • To such a degree
  • conjunction
  • Used to connect a noun clause
  • Used to introduce an adverbial clause
  • Used to introduce a noun clause
  • determiner
  • Used as a noun to refer to something
  • pronoun
  • Referring an object far away
  • Used to refer to the relative pronoun ‘which’

what

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US / wɒt /

UK / hwɑt, hwʌt, wɔt, wʌt,hwət, wət /

A1
  • pronoun
  • Thing or things that; the same kind as
  • Used to emphasize something you are about to say
  • adjecitve
  • Used to refer to a particular amount, or number
  • Used to place emphasis on a particular quality
  • adverb
  • To a certain degree
  • determiner
  • Question words used for asking for information
  • exclamation
  • Used to express excitement, shock, or surprise
  • Used to ask people to repeat something they said

sit

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US / sɪt /

UK / sɪt /

A1
  • verb
  • To take an exam
  • To be in a resting position on a chair
  • To provide seating for people
  • To remain in a still position while being painted

second

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US / 'sekənd /

UK / ˈsɛkənd /

A1
  • adjecitve
  • 2nd; the one following first
  • noun
  • Unit of time; one sixtieth of a minute
  • Short period of time that you wait for someone
  • (Do) soon

number

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US / ˈnʌmbə(r) /

UK / ˈnʌmbɚ /

A1
  • noun
  • Symbols such as 1, 2, 56, 793
  • Particular song or dance performed during a show
  • Total quantity or amount of things
  • verb
  • To put numbers on things
  • To assign a sequence within a group, series, set
  • To claim to be part of a larger group, series, set

redefine

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US / ˌri:dɪˈfaɪn /

UK / ˌriːdɪˈfaɪn /

B1
  • verb
  • To give a new explanation of or reason for
  • To set or mark the limits of something again

case

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US / keɪs /

UK / kes /

A1
  • noun
  • Container used to carry things, e.g. clothes
  • Set of facts about a crime
  • Set of facts about an event
  • Example or instance of something
  • verb
  • To find out about a place, as in planning to steal

find

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US / faɪnd /

UK / faɪnd /

A1
  • noun
  • Object discovered by chance
  • Things that have been discovered from searching
  • verb
  • To become aware of something that is happening
  • To discover or meet by chance
  • To decide if someone is guilty of a crime, or not
  • To learn through study, research, or effort
  • To discover something by looking for it

mean

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US / mi:n /

UK / min /

A1
  • adjecitve
  • Being good at
  • Nasty; unkind
  • Not liking to spend money; cheap; stingy
  • noun
  • Average of a set of numbers
  • verb
  • To express a particular idea or thought
  • To intend to do something in particular
  • To have a particular meaning or value

recursion

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US / rɪˈkɜ:ʃn /

UK / rɪˈkɜ:rʃn /

A1
  • noun
  • Expression such that each term is generated by repeating a particular mathematical operation

type

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US / taɪp /

UK / taɪp /

A1
  • noun
  • Printed letters or blocks used for printing them
  • Group of things or people sharing common features
  • verb
  • To identify something belonging to a group
  • To write by touching keys on a keyboard

comment

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US / 'kɒment /

UK / ˈkɑmɛnt /

A2
  • noun
  • Something you say, giving an opinion; remark
  • verb
  • To say something that gives your opinion

down

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US / daʊn /

UK / daʊn /

A1
  • adjecitve
  • Being sad, sick, or unhappy
  • Not operating, working, or functioning as expected
  • adverb
  • In a sitting or lying position
  • Towards or on the ground, floor, or bottom
  • Written or copied onto a piece of paper or book
  • noun
  • A period of play in American Football
  • The soft, smooth hairs that cover a bird's body
  • preposition
  • Along something's path, course, or direction
  • Going from a higher position to a lower position
  • verb
  • To eat or drink very quickly and without stopping

then

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US / ðen /

UK / ðɛn /

A1
  • adverb
  • A time that is not now
  • Following another thing in time or arrangement
  • Following on reasonably from what was just stated
  • At that time, not now

boil

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US / bɔɪl /

UK / bɔɪl /

A2
  • verb
  • To become extremely angry or excited
  • To cook in very hot water
  • To make liquids hot so they turn to gas

each

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US / i:tʃ /

UK / itʃ /

A1
  • determiner
  • Every one of two or more things
  • pronoun
  • Per one person or thing

happen

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US / 'hæpən /

UK / ˈhæpən /

A1
  • verb
  • To take place or occur

factorial

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US / fækˈtɔ:riəl /

UK / fækˈtɔriəl, -ˈtor- /

A1
  • adjecitve
  • Concerning factors or factorials

let

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US / let /

UK / lɛt /

A1
  • verb
  • To allow someone to do something
  • Introducing a suggestion to do something together
  • To rent a house, etc. to others

little

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US / 'lɪtl /

UK / ˈlɪtl /

A1
  • adjecitve
  • Being short in length of time
  • Not great in size, amount, or degree; small
  • Being very young or younger than others
  • adverb
  • By an amount or degree that is not very much
  • Not often; rarely
  • noun
  • A person's name

the

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US / ðə /

UK / ðə /

A1
  • article
  • Used to refer to something already mentioned
  • Used to show there is only one of something
  • determiner
  • Used to describe all of a family

also

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US / 'ɔ:lsəʊ /

UK / ˈɔlso /

A1
  • adverb
  • In addition; too; in a similar way

kind

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US / kaɪnd /

UK / kaɪnd /

A1
  • adjecitve
  • In a caring and helpful manner
  • friendly and considerate
  • noun
  • One type of thing

iterate

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US / 'ɪtəreɪt /

UK / ˈɪtəˌret /

A1
  • verb
  • To utter or perform something repeatedly

how

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US / haʊ /

UK / haʊ /

A1
  • adjecitve
  • To what degree? in what amount?
  • adverb
  • (Used to explain the way to do something)
  • exclamation
  • For what purpose or reason?
  • (Used to ask someone or something's condition)

you

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US / jʊ /

UK / ju /

A1
  • pronoun
  • Person someone is speaking or writing to
  • Person or people in general

conditional

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US / kənˈdɪʃənl /

UK / kənˈdɪʃənəl /

A2
  • adjecitve
  • Depending (on)
  • noun
  • Clause or sentence beginning with 'if' or 'unless'

into

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US / 'ɪntə /

UK / ˈɪntu /

A1
  • preposition
  • Moving or going inside something
  • In the same direction as; in the direction of
  • So as to become; taking the state of

other

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US / 'ʌðə(r) /

UK / ˈʌðər /

A1
  • adjecitve
  • A thing different from that mentioned
  • determiner
  • (Something) else; not the first (one)
  • pronoun
  • Being the one and only thing of that category

one

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US / wʌn /

UK / wʌn /

A1
  • pronoun
  • You; we; people in general; someone
  • The thing or person previously referred to
  • adjecitve
  • Used to refer to people generally
  • Being a strong example of (something mentioned)
  • number
  • Number 1

than

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US / ðən /

UK / ðən /

A1
  • conjunction
  • Used to compare two things that are not equal

answer

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US / 'ɑ:nsə(r) /

UK / ˈænsɚ /

A1
  • noun
  • Reply to a question someone asks
  • Solution to a problem or test question
  • verb
  • To reply to a question someone asks
  • To solve a test question or a problem

less

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US / les /

UK / lɛs /

A1
  • adjecitve
  • Smaller in amount or degree
  • adverb
  • To a smaller degree
  • noun
  • A smaller amount
  • preposition
  • With the subtraction of

deep

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US / di:p /

UK / dip /

A1
  • adjecitve
  • Complex and important
  • Extreme or intense
  • Going far down from the surface
  • Low in pitch, as a sound
  • adverb
  • At a certain distance beneath the surface

level

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US / 'levl /

UK / ˈlɛvəl /

A2
  • adjecitve
  • (Sports) equal to another
  • Being steady and determined (e.g. a voice)
  • noun
  • Specific height of something
  • Amount of ability you have compared to others
  • Floor or deck within a building
  • Tool used to determine if something is lying flat
  • verb
  • To aim a gun at someone
  • To destroy a building; flatten an area completely
  • To make things flat or even
  • To make a score equal to another, in sports

eventual

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US / ɪˈventʃuəl /

UK / ɪˈvɛntʃuəl /

B2
  • adjecitve
  • Coming or happening at a later or end of the time

program

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US / 'prəʊɡræm /

UK / ˈproˌɡræm, -ɡrəm /

A1
  • noun
  • Small book of events in a play, concert or movie
  • A plan or schedule of events
  • Series of classes at a college or university
  • A computer application
  • TV show
  • verb
  • To make someone act or think in a certain way
  • To write computer code for a piece of software

this

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US / ðɪs /

UK / ðɪs /

A1
  • adjecitve
  • Used to indicate something already been discussed
  • Used to indicate something happening around now
  • adverb
  • An indication by a physical motion or gesture
  • A specific amount of
  • determiner
  • Person, thing, or idea near you
  • pronoun
  • Person, thing that has already been discussed

make

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US / meɪk /

UK / mek /

A1
  • noun
  • Product made by a particular company; brand
  • verb
  • To arrange or prepare something e.g. dinner
  • To get to (a place) on time
  • To gain the status of (teacher, lawyer, etc.)
  • To create something by putting things together
  • To earn a certain amount of money at a job
  • To cause or force a person to do something
  • To cause something to happen or be formed

run

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US / rʌn /

UK / rʌn /

A1
  • noun
  • Journey between two places made by ship or car
  • Series of similar things or successes and failures
  • Act of running; exercise of running
  • verb
  • To depart or travel according to a schedule
  • To cause an animal to move in a certain direction
  • (Of an engine) to be operating
  • To start or use a computer program
  • To flow in a certain direction, like a liquid
  • To manage or operate a business
  • To operate or drive something
  • (Of a road) to go from one place to another
  • To move your legs faster than walking

cool

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US / ku:l /

UK / kul /

A1
  • adjecitve
  • Steady and calm when facing difficulties
  • Almost cold; not warm or hot
  • Smart or stylish in a way (young) people admire
  • Unfriendly in an indirect way; distant
  • verb
  • To make something decrease in temperature
  • (Of an emotion, etc.) to become less strongly felt

computer

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US / kəmˈpju:tə(r) /

UK / kəmˈpjutɚ /

A1
  • noun
  • Machine for storing data, accessing the internet

interpret

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US / ɪn'tɜ:prɪt /

UK / ɪnˈtɚprɪt /

A2
  • verb
  • To express so that others understand it
  • To translate what is said into another language

prompt

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US / prɒmpt /

UK / prɑmpt /

B1
  • adjecitve
  • Fast; in a quick manner; without delay
  • noun
  • Message on a computer requiring attention
  • Encouragement to ask someone else to talk
  • verb
  • To display a message to requires a user to act
  • To say something to encourage someone else to talk
  • To remind an actor of his or her lines (words)
  • To cause something to occur; be the cause of

voodoo

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US / ˈvu:du: /

UK / ˈvudu /

A1
  • noun
  • Cult practiced by sorcery and spirit possession

few

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US / fju: /

UK / fju /

A1
  • pronoun
  • Not many, a small number

just

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US / dʒʌst /

UK / dʒʌst /

A1
  • adjecitve
  • Proper or appropriate; as is deserved
  • Doing or being what is right or fair
  • Legally correct; having enough evidence
  • adverb
  • Almost; nearly
  • Exactly at the time of
  • Exactly (the same as, like)

recursively

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US / /

UK / /

A1
  • adverb

for

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US / fə(r) /

UK / fɔr,fə /

A1
  • preposition
  • Used to show the purpose, or need of something

through

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US / θru: /

UK / θru /

A2
  • adjecitve
  • having finished using or doing something
  • adverb
  • From the beginning of something until the end
  • preposition
  • Over, in, across an entire thing or place
  • Allowing you to pass between, or to
  • By a particular way or process; by the use of

time

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US / taɪm /

UK / taɪm /

A1
  • noun
  • Speed at which music is played; tempo
  • Point as shown on a clock, e.g. 3 p.m
  • Number of hours, minutes needed to do something
  • Occasion when something happens
  • Period or occasion that something occurred
  • Period in history or the past
  • Something measured in minutes, hours, days, etc.
  • How long an event takes; duration
  • verb
  • To check speed at which music is performed
  • To choose a specific moment to do something
  • To measure how long an event takes, e.g. a race
  • To schedule something to occur at a specific moment

why

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US / waɪ /

UK / hwaɪ, waɪ /

A1
  • adverb
  • Question word to ask for a reason
  • exclamation
  • (Used to express surprise or approval)

situation

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US / ˌsɪtʃuˈeɪʃn /

UK / ˌsɪtʃuˈeʃən /

A1
  • noun
  • Place, position or area that something is in
  • Circumstance or condition surrounding an event
  • An unexpected problem or difficulty

diagram

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US / 'daɪəɡræm /

UK / ˈdaɪəˌɡræm /

B1
  • noun
  • A drawing intended to explain how something works
  • verb
  • To show or explain something by drawing a picture

exact

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US / ɪɡ'zækt /

UK / ɪɡˈzækt /

A2
  • adjecitve
  • Completely correct; accurate; specific
  • verb
  • To get something, sometimes using force

well

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US / wel /

UK / wɛl /

A1
  • adjecitve
  • Being in a fortunate, good condition or state
  • Healthy and in good condition
  • adverb
  • In an acceptable, proper, or successful manner
  • In a complete, total, or full manner
  • A great and considerable degree
  • In a successful way, in a good or satisfactory way
  • exclamation
  • Used to begin or continue a particular statement
  • Used to show you want to start saying something
  • Used to express that you are waiting for a reply
  • You say this to change the topic of a conversation
  • Used to indicate you are making a final remark
  • noun
  • Long deep hole in the ground to get water
  • verb
  • To cause your eyes to fill with tears

define

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US / dɪ'faɪn /

UK / dɪˈfaɪn /

A2
  • verb
  • To explain the meaning of words
  • To set or mark the limits of something

stuff

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US / stʌf /

UK / stʌf /

A1
  • noun
  • Generic description for things, materials, objects
  • verb
  • To push material inside something, with force

those

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US / ðəʊz /

UK / ðoz /

A1
  • determiner
  • The people or things we are talking about
  • pronoun
  • The objects far from the speaker

whether

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US / ˈweðə(r) /

UK / ˈhwɛðɚ, ˈwɛð- /

A1
  • conjunction
  • If something will happen or not

definition

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US / ˌdefɪˈnɪʃn /

UK / ˌdɛfəˈnɪʃən /

A2
  • noun
  • Explanation of word's meaning, as in dictionaries
  • The sharpness of an image on a screen
  • Visual clearness in a photo or on a screen

equal

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US / 'i:kwəl /

UK / ˈikwəl /

A1
  • adjecitve
  • Same in shape, size, or number
  • verb
  • To add up or be the same as

neat

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US / ni:t /

UK / nit /

A2
  • adjecitve
  • That you approve of; cool
  • (Of alcohol) not weakened with water or a mixer
  • Not messy; clean and orderly; simple and effective

now

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US / naʊ /

UK / naʊ /

A1
  • adverb
  • At the present time or moment
  • Right away or in the next possible moment
  • Used to refer to something that just happened
  • Time between the present and a moment in the past
  • conjunction
  • Resulting from or because of something

decent

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US / ˈdi:snt /

UK / ˈdisənt /

B1
  • adjecitve
  • Being fairly good; acceptable

can

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US / kæn /

UK / kən,kæn /

A1
  • noun
  • A metal container for storing food
  • other
  • Able to; have the skill to; have the time to
  • verb
  • To have permission to
  • To be possible to do
  • To preserve food by sealing it in a metal container

behaviour

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US / bɪˈheɪvjə(r) /

UK / bɪˈhevjɚ /

A1
  • noun
  • The way a person or thing acts; manner

same

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US / seɪm /

UK / sem /

A1
  • adjecitve
  • Being equal in quality and amount
  • Identical; not different
  • Not changing; constant

save

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US / seɪv /

UK / sev /

A1
  • noun
  • Preventing a player in a game from scoring a goal
  • preposition
  • Except; not including
  • verb
  • To make your computer keep a file
  • To keep for future use
  • To make something unnecessary; prevent
  • To keep money so that you will have it later
  • To keep something for future use, such as money
  • To keep or rescue someone or something from harm
  • To prevent a player in a game from scoring a goal
  • To avoid the unnecessary waste of energy, etc.

crazy

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US / 'kreɪzɪ /

UK / ˈkrezi /

A2
  • adjecitve
  • Mentally ill; mad
  • Not being sensible or practical
  • Really like someone or something very much
  • noun
  • Person acting in a manner that is strange and odd

video

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US / 'vɪdɪəʊ /

UK / ˈvɪdiˌo /

A2
  • adjecitve
  • Of a moving film, with sound
  • noun
  • Recording capturing action with sound
  • verb
  • To make a moving film of, with sound

want

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US / wɔnt /

UK / wɑnt, wɔnt /

A1
  • noun
  • Something you desire or wish for
  • State or condition of poverty
  • verb
  • To desire or wish for something; hope for a thing

really

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US / ˈri:əli /

UK / ˈriəˌli, ˈrili /

A1
  • adverb
  • Used to stress something that is said; definitely
  • In a true or accurate manner
  • Very

not

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US / nɒt /

UK / nɑt /

A1
  • adverb
  • Word indicating the negative
  • (Used to form the negative of verbs)

our

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US / 'aʊə(r) /

UK / aʊr /

A1
  • determiner
  • Belonging to us

maybe

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US / ˈmeɪbi /

UK / ˈmebi /

A1
  • adverb
  • Possibly but not certainly; perhaps

but

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US / bət /

UK / bʌt,bət /

A1
  • conjunction
  • Used before you say something different, opposite

especially

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US / ɪˈspeʃəli /

UK / ɛˈspɛʃəli, ɪˈspɛʃ- /

A1
  • adverb
  • More than usual; extremely

give

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US / ɡɪv /

UK / ɡɪv /

A1
  • noun
  • Degree of flexibility in something, a material
  • verb
  • To hand over or present something to someone
  • To cause someone to have or experience something

reason

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US / 'ri:zn /

UK / ˈrizən /

A1
  • noun
  • Ability to think about facts and form a judgment
  • Explanation for why something occurred or was done
  • verb
  • To think and make conclusions in a logical manner

rid

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US / rɪd /

UK / rɪd /

A2
  • verb
  • To cause to no longer have (pest, problem)

complicated

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US / 'kɒmplɪkeɪtɪd /

UK / ˈkɑmplɪˌketɪd /

B1
  • adjecitve
  • Difficult to do, understand or use
  • verb
  • To make more difficult to do, understand or use

exactly

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US / ɪgˈzæktli /

UK / ɪɡˈzæktli /

A1
  • adverb
  • No more and no less than; precisely

science

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US / 'saɪəns /

UK / ˈsaɪəns /

A2
  • noun
  • Study of the physical world, based on facts

should

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US / ʃʊd /

UK / ʃʊd /

A1
  • other
  • Used to indicate what is proper or reasonable

always

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US / 'ɔ:lweɪz /

UK / ˈɔlwez,-wɪz,-wiz /

A1
  • adverb
  • For a very long time
  • At all times; in every situation
  • For ever

already

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US / ɔ:lˈredi /

UK / ɔlˈrɛdi /

A1
  • adverb
  • Having happened or been done before this time

itself

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US / ɪtˈself /

UK / ɪtˈsɛlf /

A1
  • pronoun
  • Referring to it

will

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US / wɪl /

UK / wɪl /

A1
  • noun
  • Desire or choice of someone
  • Document saying who gets your money when you die
  • Strong desire to do something; determination
  • Desire to do something; strong wish to do
  • other
  • Used with verbs to express the future
  • verb
  • To leave property to someone after your death
  • To use mental effort to make something happen
  • Am (is, are) likely to do
  • To influence someone to do something
  • To make something happen by strongly wanting it

actually

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US / ˈæktʃuəli /

UK / ˈæktʃuəli /

A1
  • adverb
  • Used to add new (often different) information

use

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US / ju:s /

UK / ju:s /

A1
  • noun
  • Ability to employ something
  • Need to enable it to work
  • Permission to do something with something
  • Act of spending money
  • Operation of a machine for its function
  • verb
  • To have; to eat, drink, consume etc.
  • To need to operate or work
  • To operate a machine, e.g. a computer
  • To treat a person badly
  • To do something with, for a task or purpose

write

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US / raɪt /

UK / raɪt /

A1
  • verb
  • To compose letters and words on paper or a screen
  • To invent or create a computer program
  • To create a song or piece of music

here

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US / hɪə(r) /

UK / hɪr /

A1
  • adverb
  • In this place; at this location, position or time

nugget

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US / ˈnʌgɪt /

UK / ˈnʌɡɪt /

C1
  • noun
  • Small, solid lump (of gold, chicken, wisdom etc.)

small

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US / smɔ:l /

UK / smɔl /

A1
  • adjecitve
  • Little in size; not big
  • (Of letters) not written in capital letters
  • Being insignificant or minor
  • (Of a business) with few people or things; local
  • (Of voice) being soft and quiet
  • (Of a child) being young

try

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US / traɪ /

UK / traɪ /

A1
  • noun
  • Act of putting the ball over the rugby goal line
  • verb
  • To make an effort, to attempt to do something
  • To examine someone or something in a court of law
  • To test to see if it is good or you like it
  • To make a person go through hardship; test
  • To examine something to see if it works

once

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US / wʌns /

UK / wʌns /

A1
  • adverb
  • One time; one instance
  • At a time in the past
  • conjunction
  • When; as soon as

matter

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US / 'mætə(r) /

UK / ˈmætɚ /

A1
  • noun
  • Material all things are made of that fills space
  • Problem or reason for concern
  • verb
  • To be of great importance; to count

any

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US / 'enɪ /

UK / ˈɛni /

A1
  • adjecitve
  • One, or some, no matter which
  • pronoun
  • One (thing) of many; some

think

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US / θɪŋk /

UK / θɪŋk /

A1
  • verb
  • To have an idea about something without certainty
  • To have an idea, opinion or belief about something

and

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US / ənd /

UK / ənd, ən,ænd /

A1
  • conjunction
  • Used to refer to two or more things
  • Plus; in addition; on top of that
  • Used to introduce an action that follows another

base

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US / beɪs /

UK / bes /

A2
  • noun
  • Place military personnel live, train, and operate
  • Bottom part of an object that touches a surface
  • Unit of counting, e.g. 10 for counting
  • Most important idea or ingredient to add others
  • Origin or start from which something came
  • Main place where an organization or a person works
  • verb
  • To use as the starting point or origin for
  • To have as the main location for (company, etc.)

hopefully

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US / ˈhəʊpfəli /

UK / ˈhopfəli /

A2
  • adverb
  • In a manner wishing something to happen

rest

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US / rest /

UK / rɛst /

A1
  • noun
  • Time when one relaxes, sleeps, or is inactive
  • State in which there is a lack of motion
  • Part of something remaining after some was used
  • verb
  • To stop working or avoid activity to recover
  • (Of dead person) to lie in a grave
  • To lean, support or place something against
  • To not be tired because you had enough sleep

anything

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US / ˈeniθɪŋ /

UK / ˈɛniˌθɪŋ /

A1
  • pronoun
  • A thing of any kind

from

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US / frəm /

UK / frʌm, frɑm,frəm /

A1
  • preposition
  • Starting at a particular place, time or level

minus

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US / ˈmaɪnəs /

UK / ˈmaɪnəs /

A2
  • adjecitve
  • Being close to the bottom of a letter grade
  • noun
  • Negative quality; disadvantage
  • Sign that indicates subtraction
  • preposition
  • Being less than zero in number
  • Used when subtracting one number from another
  • verb
  • To take one number away from another; subtract

out

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US / aʊt /

UK / aʊt /

A1
  • adverb
  • No longer stylish (e.g. fashion)
  • Away from home, business, or the usual place
  • In a direction/movement away from inside or center
  • noun
  • Act when a batter cannot continue playing
  • verb
  • To tell people a secret

over

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US / 'əʊvə(r) /

UK / ˈovɚ /

A1
  • adverb
  • Finished; no longer happening
  • Towards the ground/away from a standing position
  • noun
  • A set of six consecutive balls bowled in cricket
  • other
  • Finished
  • preposition
  • Showing the relation when a thing is above another
  • On or covering something
  • Above or across something
  • More than you need
  • From one side to the other
  • In the direction of; toward

call

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US / kɔ:l /

UK / kɔl /

A1
  • noun
  • A order or request for action
  • The sound an animal makes, often when in danger
  • A correct prediction, e.g. a decision in a game
  • A short visit to a place or person
  • A decision by a referee or umpire in a game
  • verb
  • To make a request or order for action
  • (Animal) to make sounds to warn of danger
  • To announce the date of an election
  • To make a judgment about something
  • To give someone or something a name
  • To guess in advance the result or outcome
  • To visit a place or person for a short time
  • To phone someone
  • To speak, announce or shout in a loud voice

where

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US / hwɛə /

UK / hwɛr, wɛr /

A1
  • conjunction
  • At or in the place which
  • In whatever place
  • pronoun
  • Word you use to ask the location of something

keep

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US / ki:p /

UK / kip /

A1
  • noun
  • Large, strong tower in the middle of a castle
  • Money spent on you so you can live in a place
  • verb
  • To continue doing something; not to stop
  • To stop balls going in a goal in sports
  • To not give back or return something
  • (Of food) to not spoil or not rot
  • To take possession of something to own, e.g. a pet
  • To have and continue to hold something
  • To do something that you have promised or agreed
  • To stay in a certain place or condition
  • To maintain the rules

variable

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US / ˈveəriəbl /

UK / ˈveriəbl /

A2
  • adjecitve
  • Having the ability to change or vary
  • noun
  • Mathematical quantity with several values

something

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US / ˈsʌmθɪŋ /

UK / ˈsʌmθɪŋ /

A1
  • adverb
  • In some degree or measure
  • noun
  • a person or thing of some value or consequence
  • pronoun
  • Thing that is not yet known or named
  • Approximately

affect

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US / ə'fekt /

UK / əˈfɛkt /

A2
  • verb
  • To cause a change in something else

put

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US / pʊt /

UK / pʊt /

A1
  • phrasal verb
  • to make a light stop shining by pressing or moving a switch
  • verb
  • To move or place a thing in a particular position
  • To rate something in importance or value
  • To write or say something in a certain manner

all

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US / ɔ:l /

UK / ɔl /

A1
  • adverb
  • Completely; totally
  • determiner
  • Being every one of something
  • pronoun
  • 100% of something; the complete amount

correctly

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US / kə'rektlɪ /

UK / kəˈrɛktlɪ /

A2
  • adverb
  • In an accurate or correct manner

return

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US / rɪ'tɜ:n /

UK / rɪ'tɜ:rn /

A1
  • adjecitve
  • Do again; repeated
  • noun
  • Faulty or unwanted product sent back to a company
  • Enter key; the main key on the computer keyboard
  • Profit made as a result of a business activity
  • Process of going back to a previous way or state
  • verb
  • To hit something back to the other player or team
  • To come back after being away from somewhere
  • To repay someone's actions, kindness etc.
  • To put, bring, take, give, or send something back
  • To occur again

else

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US / els /

UK / ɛls /

A1
  • adverb
  • Otherwise; if you fail to
  • (Of person place thing etc.) besides; in addition

figure

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US / ˈfiɡə /

UK / ˈfɪɡjɚ /

A1
  • noun
  • Your body shape
  • Numbers in a calculation
  • Doll-like thing meant to represent a person
  • Picture or diagram giving information in a text
  • Person who is very important or famous
  • Shape of a person seen indistinctly or in outline
  • Amount that is expressed in numbers
  • verb
  • To appear in a game, play or event
  • To calculate how much something will cost
  • To understand after thinking; work out

implement

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US / ˈɪmplɪment /

UK / ˈɪmpləmənt /

B1
  • noun
  • A tool
  • verb
  • To start to do something you plan to do

regardless

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US / rɪˈgɑ:dləs /

UK / rɪˈɡɑrdlɪs /

A2
  • adverb
  • Without being affected or concerned by something

way

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US / weɪ /

UK / we /

A1
  • adverb
  • Used to emphasize the amount of something
  • noun
  • Particular aspect of something being thought about
  • One of various choices that could be made
  • Particular existing condition or state
  • (Often long) distance or length of time
  • How something is done
  • Route to go to a place
  • Small street
  • Usual behavior, emotions or habits of someone

change

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US / tʃeɪndʒ /

UK / tʃendʒ /

A1
  • noun
  • Exchange of one set of clothes for another
  • Money in the form of coins instead of paper
  • Money returned after giving too much
  • Act of making or becoming something else
  • verb
  • To exchange one set of clothes for another
  • To exchange one kind of money for another
  • To replace something with another thing
  • To make or become something else
  • To go from one train, bus, etc. and go to another

simple

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US / 'sɪmpl /

UK / ˈsɪmpəl /

A1
  • adjecitve
  • Not hard to understand or do; not complex
  • Having only a few parts; not complex
  • Being ordinary or normal
  • Being plain; without a lot added for style

execute

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US / ˈeksɪkju:t /

UK / ˈɛksɪˌkjut /

B1
  • verb
  • To kill someone, usually as an official punishment
  • To perform a plan or action

gut

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US / ɡʌt /

UK / ɡʌt /

B1
  • noun
  • Stomach and internal organs of digestion
  • Guts courage; emotional strength
  • verb
  • To destroy the inside of a building , e.g. by fire
  • To remove the internal parts of an animal or fish

original

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US / ə'rɪdʒənl /

UK / əˈrɪdʒənəl /

A2
  • adjecitve
  • Being first made, thought or performed; fresh
  • Being unique or thinking differently from others

they

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US / ðeɪ /

UK / ðe /

A1
  • pronoun
  • Two or more people, animals, or things

very

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US / 'verɪ /

UK / ˈvɛri /

A1
  • adjecitve
  • Concerning a large degree or amount
  • adverb
  • A lot; much; many
  • Used to stress or emphasize a noun

introduce

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US / ˌɪntrəˈdju:s /

UK / ˌɪntrəˈdus, -ˈdjus /

A1
  • verb
  • To open an essay to set the scene
  • To guide or explain something, e.g. a town
  • To begin the use of a new thing or practice
  • To make someone known to another by name
  • To insert or put something inside another thing

iterative

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US / 'ɪtərətɪv /

UK / 'ɪtəˌreɪtɪv /

C1
  • adjecitve
  • Marked by iteration; repeating

bit

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US / bɪt /

UK / bɪt /

A1
  • noun
  • Device put in a horse's mouth to control it
  • Small piece of something
  • verb
  • (E.g. of fish) to take bait and be caught

look

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US / lʊk /

UK / lʊk /

A1
  • noun
  • Person's beauty or physical attractiveness
  • Particular style of dress, clothes, or appearance
  • The way someone, something appears to be
  • Act of searching for or examining something
  • verb
  • To appear to be; seem

multiply

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US / ˈmʌltɪplaɪ /

UK / ˈmʌltəˌplaɪ /

B1
  • verb
  • To increase in number by reproducing/having babies
  • To increase something by a large quantity
  • To have increased by a large quantity
  • To calculate two numbers e.g. 2 x 4

rewrite

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US / ˌri:'raɪt /

UK / riˈraɪt /

A2
  • verb
  • To write again to improve, or correct errors

prove

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US / pru:v /

UK / pruv /

A2
  • verb
  • To demonstrate truth by providing evidence

old

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US / əʊld /

UK / old /

A1
  • adjecitve
  • Having existed for a long time, not young or new
  • Age of a person since birth

work

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US / wɜ:k /

UK / wɚk /

A1
  • adjecitve
  • Activity completed in order to make money
  • noun
  • The product of some artistic or literary endeavor
  • Everything created by an author, artist, musician
  • Activity you do in order to make money
  • Place of employment
  • Final product or result of a some labor or effort
  • verb
  • To bring into a specific state of success
  • To be functioning properly, e.g. a car
  • To do your job in your company or workplace
  • To make an effort to do something
  • To operate a machine or device

worry

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US / ˈwʌri /

UK / ˈwɜ:ri /

A1
  • noun
  • Something that causes trouble or concern
  • verb
  • To cause concern or trouble over something

add

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US / æd /

UK / æd /

A1
  • verb
  • To include as well
  • To put two things or numbers together, e.g. 2+2

take

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US / teɪk /

UK / tek /

A1
  • noun
  • Filming of a single scene for TV or the movies
  • verb
  • To accept something that is offered
  • To use a method of traveling, e.g. a bus or train
  • To use a camera to make (a photo)
  • To pick up something and go away with it
  • To study a subject in school
  • To attempt to pass (an exam)
  • To require a certain amount of time, money, space
  • Subtitles section
  • What I want to do in this video is introduce you to what I think is one of the neatest ideas in computer science, and that is recursion.
  • So the way that we've defined this factorial function in the last few videos is actually an iterative definition.
  • We are iterating through different values for this variable i, and then we're essentially taking those values, adding one, then multiplying those times our original product.
  • And when we keep iterating through all of that, our eventual product has all of the values from 1 through the number multiplied by each other, and they're all sitting in this variable product.
  • What I'm going to do here is rewrite this program.
  • And what's cool about functions-- I'm going to rewrite this function.
  • What's cool about functions are this function, we just say, look, it returns a factorial of a number.
  • We don't care how this is actually written.
  • And so anything that's using this function call, no matter how I implement it, as long as I implement it correctly, it shouldn't worry about it.
  • So as long as I implement the guts of this function right, even if I do it in a very different way, it shouldn't affect the behavior of any of the functions that call it.
  • So let's go ahead and try to define this function recursively.
  • And I think you're going to find this slightly fascinating.
  • So I'm going to do it a little bit different.
  • We're going to put some conditionals in here as well.
  • So I'm going to say-- so it's almost-- in some ways, recursion is really deep and complicated, and on some levels, it's way simpler than anything else.
  • So let me just put all of this stuff down there.
  • So I'm going to say, look, if the number-- you always want to think about a base case.
  • What's a situation where kind of the nugget or the smallest values we can put into for a number that'll give us a decent response?
  • So we'll say, look, if number is-- let's say if it's less than or equal to 1, so if it's less than or equal to 1, let's just return.
  • Well, then it's factorial.
  • Let's just return 1, especially if we want to have the same behavior as the old function.
  • The old function, regardless of whether we put a 1 there, a 0 there, or actually, even if we put a negative 1 or negative 2 there, it always gave us the factorial being equal to 1.
  • So that's exactly what we're doing over here.
  • We're returning 1 if the number is less than 1.
  • And this also defines our base case.
  • I can even label it here.
  • So let me label-- this is our base case.
  • And you'll see what I mean for a second by base case.
  • And what I'm about to do now, this is the really exciting part about recursion.
  • If the number is not less than or equal to 1, so I could write l if-- well, maybe I'll just write l, actually.
  • So if the number is not less than or equal to 1, I'm going to return something different.
  • And what I'm going to return is that number times the factorial-- times the factorial of one less than that number.
  • Now, the reason why this is fascinating and cool and all the rest is I just defined something using that something.
  • So I just defined a function called factorial, and I defined it using the definition of the function factorial.
  • It is referring to itself.
  • This is what recursive functions do.
  • But if you think about it-- and I'll diagram it out in more detail in the next video, so hopefully it makes a little bit more sense-- it should kind of work.
  • Because if you put a 1 or a 0 in for a number, it'll just return 1.
  • What happens if the number is 2?
  • Well, if the number is 2, it'll say, look, the number is not less than our 1, so I'll go over here.
  • So it says it'll return 2 times factorial of 2 minus 1, or factorial of 1.
  • And then it'll call factorial again, and factorial of 1 is just 1, so it'll return 2 times 1.
  • So that'll work out for 2.
  • Try it for 3.
  • If you do a factorial of 3, it'll go down to this clause over here, because 3 is not less than or equal to 1, and it'll return 3 times the factorial of 3 minus 1, which is 2, the factorial of 2.
  • Well, we know it already returns the right answer for the factorial of 2, so it'll return 3 times 2, which is 6, which is a factorial of 3.
  • So hopefully you're getting the gist of it.
  • Factorial of 4 is going to work for the exact same reason.
  • It's going to boil down to 4 times the factorial of 3.
  • We know that it works for the factorial of 3.
  • And just to prove to you that I'm not doing some type of crazy voodoo, and that this will actually work, let's try to run the program.
  • Let's try to run the program right here.
  • This is some stuff that I was doing beforehand.
  • Let me just get rid of that.
  • So let's just run the program.
  • So all I've done is I've redefined the factorial function, but I've redefined it recursively.
  • I won't have to change the comments.
  • So let me save it, and let's interpret this program.
  • Let's execute it and see if it does what we need it to do.
  • All right.
  • So they're prompting us for something.
  • Let's take the factorial of 5-- 120.
  • And so once again, our factorial program, no matter what we put in there, it gives us the right answer.
  • But what's really cool is it's now doing it recursively.
  • When I do factorial of 6, say, OK, factorial of 6.
  • Is 6 less than or equal to 1?
  • Well, no it's not, so it goes to this else clause right over here.
  • So then it says return 6 times the factorial of 5.
  • Then it says, OK, let me remember 6 times the factorial of 5.
  • Let's figure out what the factorial of 5 is.
  • Well, factorial of 5 is going to be 5 times the factorial of 4.
  • And then that factorial of 4 is 4 times the factorial of 3, all the way down to the factorial of 1, which is 1.
  • And so it'll actually return 6 times 5 times 4 times 3 times 2 times 1.