'can' and 'could'

Level: beginner

Possibility and impossibility

We use could to show that something is possible, but not certain:

They could come by car. (= Maybe they will come by car.)
They could be at home. (= Maybe they are at home.)

We use can to make general statements about what is possible:

It can be very cold here in winter. (= It is sometimes very cold here in winter.)
You can easily get lost in this town. (= People often get lost in this town.)

We use can't or cannot to say that something is impossible:

That can't be true.
You cannot be serious.

Level: intermediate

We use could have to make guesses about the past:

It's ten o'clock. They could have arrived by now.
Where are they? They could have got lost.

We use could to make general statements about the past:

It could be very cold there in winter. (= It was sometimes very cold there in winter.)
You could easily get lost in that town. (= People often got lost in that town.)

We use can't have or couldn't have to say that a past event was impossible:

They know the way here. They can't have got lost!
If Jones was at work until six, he couldn't have done the murder.

Ability

Level: beginner

We use can and can't to talk about someone's skill or general abilities:

She can speak several languages.
He can swim like a fish.
They can't dance very well.

We use can and can't to talk about the ability to do something at a specific time in the present or future:

I can see you.
Help! I can't breathe.

We use could and couldn't to talk about the past:

She could speak several languages.
They couldn't dance very well.

Level: intermediate

We use could have to say that someone had the ability or opportunity to do something, but did not do it:

She could have learned Swahili, but she didn't want to.
I could have danced all night. [but I didn't]

Permission

Level: beginner

We use can to ask for permission to do something:

Can I ask a question, please?
Can we go home now?

could is more formal and polite than can:

Could I ask a question please?
Could we go home now?

We use can to give permission:

You can go home now.
You can borrow my pen if you like.

We use can to say that someone has permission to do something:

We can go out whenever we want.
Students can travel for free.

We use can't to refuse permission or say that someone does not have permission:

You can't go home yet.
Students can't travel for free.

Requests

We use could you … as a polite way of telling or asking someone to do something:

Could you take a message, please?
Could I have my bill, please?

can is less polite:

Can you take a message, please?

Offers

We use can I … to make offers:

Can I help you?
Can I do that for you?

We sometimes say I can ... or I could ... to make an offer:

I can do that for you if you like.
I could give you a lift to the station.

Suggestions

We use could to make suggestions:

We could meet at the weekend.
You could eat out tonight.

Questions and negatives

We make questions by putting the subject after can/could:

Can I ...?
Could I ...?
etc.
Can you ...?
Could you ...?

 

The negative form is can't in spoken English and cannot in written English.

We sometimes say cannot, but it is very emphatic.

The negative form of could is couldn't in spoken English and could not in written English.

can and could: possibility 1

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can and could: possibility 2

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can and could: other uses 1

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can and could: other uses 2

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Hello jino,

As it says, this use of 'can' means 'it sometimes happens' or 'it's not impossible'. Here are some more examples:

Be careful when you speak to Mr. Jones. He can be irritable! [= sometimes he is irritable]

Drive carefully in London. It can be quite dangerous. [= sometimes it is dangerous]

 

Best wishes,

Peter

The LearnEnglish Team

Submitted by mmoaazhameed on Thu, 23/06/2016 - 06:01

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Hello sir, could you please tell me how to use can/could for invitations (with example) Thank you.

Hello mmoaazhameed,

When the explanation above says 'offers and invitations', 'invitation' means essentially the same thing as 'offer'. So, for example, you could say to a person who looks lost on the street: 'Can I help you?' or 'Could I help you?' – these are offers or invitations to help.

Our sister site LearnEnglish Teens has a video that explains this grammar as well as a few additional practice exercises if you'd like to work on this more.

All the best,
Kirk
The LearnEnglish Team

Submitted by RTris on Mon, 06/06/2016 - 20:39

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I have a question about this sentence "what we would do if the world was different" could it be possible if i replace the modal "would" in the example sentence with "could". What we could do if the world was different? How the could sentence differs from the former? Im really confused with can and will although there are some particular use of these modals but sometimes they are used in a sentence in which they can mean the same. how will i know if im going to use can and will. thank you very much

Hello RTris,

Both 'would' and 'could' are possible. If we use 'would' then we are talking about our choices or decisions in a particular situation (a different world). If we use 'could' then we are talking about what is possible in that situation.

You can think of it like this: what we could do is everything that is possible; what we would do is which of those possible things we choose. For example:

If it rained I could stay at home or go out. I like walking in the rain, so I think I would go out.

 

Best wishes,

Peter

The LearnEnglish Team

Thanks for the reply. Im still a bit confusedwhat if I used would and could like this "If we dont hurry we could be late" and "if we hurry we would not be late". Is it also possible that I use would in your example "if we dont hurry we would be late"? Is this mean that if I use could this means it is proble there is chance wherein if I use would you are going to be late and sure about it? Thank you

Hello RTris,

'Could' in these examples describes possibility while 'would' describes a sure result, provided the condition is fulfilled. However, your examples are conditional forms and the forms in the second clause must agree with the verb form in the first clause:

If we dont hurry we could be late - this describes a possibility; it is possible that we will be late

"If we hurry we would not be late - this sentence is not consistent. You can say 'If we hurry we will not be late' (describing the result of a possible or likely condition) or you can change the first clause and say 'If we hurried we would not be late' (describing the result of a hypothetical or unlikely condition).

 

Best wishes,

Peter

The LearnEnglish Team

Submitted by Ahmedkhairy on Tue, 10/05/2016 - 22:47

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Hey :) 2 questions please 1-Is this grammatically correct? 2- is it better to use could or can ? "That story is the one that keeps me going whenever I hit my point or think that I ( couldn't ) do it anymore."

Hello Ahmedkhairy,

I'm not sure we'd say 'hit my point' in this way. I think 'I've had enough' would be better. The sentence would be:

That story is the one that keeps me going whenever I've had enough or think that I can't do it anymore.

I would say that can't is required here rather than couldn't as the whole sentence refers to general (present) time, not past time. We can use could with present meaning when talking about possibility, but here the meaning is ability, and when talking about ability could is used only with a past meaning.

 

Best wishes,

Peter

The LearnEnglish Team

Submitted by yurico on Thu, 05/05/2016 - 17:44

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Hello Kirk. I have a question, is it possible to use can with the verb know? Sometimes it sounds weird to me. For example in this sentences "consequently, humans can know everything about the world" isn´t it better to say human beings are able to know? Thanks.

Hello yurico,

Both 'can' and 'be able to' are possible here. For example:

There are limits to what we can know about the far reaches of the universe.

There are limits to what we are able to know about the far reaches of the universe.

Both of these sentences refer to our ability.

 

Best wishes,

Peter

The LearnEnglish Team

Submitted by shah Muzamil on Sat, 30/01/2016 - 13:43

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Hello sir Sir u can tell me about narration plz sir

Hello shah Muzamil,

Could you please be a bit more specific? For information on event recounts (which are a form of narrative) in an academic context, for example, our Writing for a purpose section has a few pages dedicated to this. If you're interested in the narrative tenses, please see our talking about the past and other pages in our English Grammar. Note there is a search box at the top of every page – press or click on the small magnifying glass.

All the best,
Kirk
The LearnEnglish Team

Submitted by Yura_Tea on Thu, 17/12/2015 - 06:39

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Could someone advise me? Which one is correct : I don't know if I COULD come tomorrow / I don't know if I CAN come tomorrow.... Thanks in advance!

Hello Yura_Tea,

Both of these are commonly used and there is little difference between them. I would say that 'can' is more likely if the invitation has been made, while 'could' is more hypothetical, and is something we might say if we do not know whether or not we will be invited.

Best wishes,

Peter

The LearnEnglish Team

Submitted by B H A R T I on Tue, 08/12/2015 - 07:45

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Hello sir, is this a correct sentence? I called you by the reference of _(name of person) will you tell me when can I come?

Hello Bharti,

No, that's not idiomatic – I'd suggest 'on the advice of someone'. The word order in the reported question is not correct: 'Will you tell me when I can come?'.

Best wishes,
Kirk
The LearnEnglish Team

Submitted by B H A R T I on Tue, 24/11/2015 - 08:54

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Hello sir, where we use 'can 'or can be?

Hello B H A R T I,

'be' is a bare infinitive, which is the form used after 'can' and other modal verbs. 

All the best,
Kirk
The LearnEnglish Team

Submitted by Ajaz ajju on Tue, 17/11/2015 - 17:45

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Hello sir, What is the difference between 1.simple past and 2.past perfect tense Please clear me where to use past perfect ? Tank you

Hello Ajaz ajju,

We have several pages on this topic.

For information on the past simple - here.

For information on the past perfect - here and here.

Best wishes,

Peter

The LearnEnglish Team

Submitted by Lamastry on Mon, 02/11/2015 - 17:21

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Hello I write this in order for you to help me clarify this. what is the difference between these following sentences: Let the whole wold should be singing and Let whole world should sing.

Hello Lamastry,

I'm afraid that neither of these clauses are grammatical in standard English. Perhaps 'Let the whole word sing'?

Best wishes,
Kirk
The LearnEnglish Team

Submitted by Lamastry on Fri, 23/10/2015 - 05:30

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Hello I heard someone saying this I'm her to confirm whether it is right or not In my opinion it is wrong "You have no marketing skills, you cant convince nobody" is it cant or can with nobody OR cant with anybody

Hello Lamastry,

You're right – the sentence you report is not standard English, though there are certainly a fair number of people, including native speakers, who say that. Here you should use 'anybody' instead of 'nobody'. See our indefinite pronouns page for more on this. And by the way, you could find this page yourself by searching for 'anybody' in our Search box.

Best wishes,
Kirk
The LearnEnglish Team

Submitted by Winson Sasongko on Tue, 22/09/2015 - 17:11

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what if I want to make a permission letter? Should I write on letter "dear sir, I would ask for your permission that I cannot attend your meeting today"? Or both of the modals are changed to would and could? Thank you

Dear Winson,

I expect you can find models of such letters by searching for them on the internet, and there are also some on these ESOLNexus and BBC pages. 'permission' is often followed by a to + infinitive, so I'd say something like '... your permission not to attend the meeting today', but check for examples on those pages for other ideas, too.

All the best,
Kirk
The LearnEnglish Team

Submitted by akatsuki on Sun, 30/08/2015 - 08:44

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What is the difference between could and may? I they both express the same thing, that is, could is used for hypothetical situation in the future. John is coming to visit. He could stay with us. John is coming to visit. He may stay with us.

Hello akatsuki,

Modal verbs can have a range of meanings in different contexts. Here, 'could' tells us that something is possible. 'May' can mean the same, or it can mean that the speaker agrees to let John stay.

Best wishes,

Peter

The LearnEnglish Team

Submitted by anuj3886 on Sun, 28/06/2015 - 10:41

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hello sir could you pls tell me, what is the difference b/w "can be find and can be found" with examples

Hello anuj,

'can be find' is not correct and 'can be found' is correct. It's the modal verb 'can' plus a passive infinitive.

All the best,
Kirk
The LearnEnglish Team

Submitted by helpinspeaking on Fri, 15/05/2015 - 15:06

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is this sentence is correct? we are waiting for the power, so we could microwave our dinner.

Hello helpinspeaking,

I would say that 'can' is needed here, as 'could' would refer to the past in this context. You could also say 'will be able to'.

Best wishes,

Peter

The LearnEnglish Team

Hello helpinspeaking,

It says just that on the page:

We use could to show that something is possible in the future, but not certain

Best wishes,

Peter

The LearnEnglish Team

Submitted by smsahand on Sun, 12/04/2015 - 07:59

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Hi there! Is this sentense true? (as a child my life could be streesful.) Regards

Hello smsahand,

'As a child my life could be stressful' is grammatically correct (good work!), but only you can tell us whether it's true or not! ('true' means 'accurate' - see the dictionary.)

All the best,
Kirk
The LearnEnglish Team

Submitted by AK47 on Tue, 24/03/2015 - 10:34

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Hi, I want to know why 3rd form of find is used in below sentence. I mean which grammar is that. The typhoid bacteria can be found in contaminated food or water. tnx

Hello AK47,

'can be found' is a passive construction consisting of the modal verb 'can' and the bare infinitive of the verb 'find' in the passive voice. On the pages that I've linked to, please note that 'found' is called a past participle - this is just another name for 'third form'.

Best wishes,
Kirk
The LearnEnglish Team

Submitted by ricrodri on Mon, 09/03/2015 - 05:13

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Can I show my writing sample to illustrate which is my question?

Hello ricrodri,

As is explained in more detail on our Help page, you're welcome to ask us a specific question about something you've written, but we don't have the time to give feedback on whole pieces of writing.

Best wishes,
Kirk
The LearnEnglish Team

Submitted by davide32 on Tue, 07/10/2014 - 08:26

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hi teacher now i studying the different between can, could, be able to or was able to ...could teacher explain to me when we used modal these? i make confusion because be able to is similar the modal...what are the tips for not mistake in sentence ? thanks teacher .

Hello davide32,

You can find information on modal verbs on our grammar pages. Click here to go to our modal verbs page, where you'll find links to pages focusing on particular modals.

Best wishes,

 

Peter

The LearnEnglish Team

Submitted by gaudgalv on Thu, 21/08/2014 - 17:43

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Adding to my previous question, I'm not sure about this one eithe "you better don't be slow, or your dreams could/ can pass you by" Which one would be more appropiate? And/or what would be the difference between them?. Thanks in advance to all the team and keep up the good job :)
Hello, Both of them are possible, but 'could' suggests more of an imaginary situation and 'can' more of a real situation. Best wishes, Adam The LearnEnglish Team

Submitted by gaudgalv on Wed, 20/08/2014 - 20:01

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Hi there! I'm doubtful about this sentence: "why should I feel fear? Fear could later become regret" using can instead would be more appropiate? Or what would be the difference?
Hi, The meaning in that sentence is covered under 'possibility' above. So 'could' sounds better in this sentence, as it's talking about something that's possible in the future, but not certain. Best wishes, Adam The LearnEnglish Team

Submitted by lapalu pramod on Fri, 15/08/2014 - 14:24

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Can you give me a summary for this lesson,please?

Submitted by Knightrider on Mon, 04/08/2014 - 19:09

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Hi there, Talking about "ability" what's the difference between "manage to" and "succeed in"? And how can they be compared to "can" or "be able to"? Thanks in advance. You're the best, guys.

Submitted by Peter M. on Mon, 04/08/2014 - 21:42

In reply to by Knightrider

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Hello Knightrider,

'Manage to' suggests that the activity was successful but difficult. 'Succeed in' suggests only that it was successful, but does not tell us if it was difficult or not.

'Can' is used for general ability, not specific achievements. 'Be able to' can be used for both general ability and specific achievements, but does not tell us if the task was easy or difficult.

I hope that clarifies it for you.

Best wishes,

 

Peter

The LearnEnglish Team