'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: Matching_MTYzNjc=
can and could: possibility 2: GapFillTyping_MTYzNjg=
can and could: other uses 1: Matching_MTYzNjk=
can and could: other uses 2: GapFillTyping_MTYzNzA=

Average

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Hello GIRIKUMAR,

As far as I am aware there is no difference in meaning between sure of and sure about. I don't know of any context where only one would be correct, though there are certain phrases where one is preferred, such as when using a reflexive pronoun (sure of yourself rather than about).

Peter

The LearnEnglish Team

Hello Sir, 1) kill him before he can kill you. 2) kill him before he kills you. Is there any difference between these two sentences. If yes then what meaning two sentences convey. Thank you.

Hello Abhinav,

In most contexts, the sentences can be used interchangeably.

Can carries the meaning of 'has the ability to', so you could imagine a situation in which you want to stop a person getting the ability to kill. For example, you might want to act so that someone is prevented from getting hold of a weapon which would make it possible for him to kill you.

Peter

The LearnEnglish Team

I can't find the function related to these uses of CAN: You can leave your hat on that chair He won't love you as much as I can I think he's angry with you but you can call him to check it out.

Hello Dayan

In the first sentence, 'can' seems to be used to give permission to someone. The second sentence seems a little odd to me (I think I'd say 'do' instead of 'can'), but I suppose it's describing an ability. In the third sentence, I'd say it's speaking about possibility.

Hope that helps!

All the best

Kirk

The LearnEnglish Team

Dear Sir, I have just registered at LearnEnglish. I am so happy that I can get my doubts clarified by the full-fledged teachers who are so responsive to whoever is in need of clear and precise answer to their questions concerned with grammar. You in fact make boring and confusing grammar interesting and easy to learn. My question is, You have said that 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. In the first sentence above, it's understandable that "can't have" is used as the verb in its preceding sentence is in the present. So is in the case of the second sentence. What if we used "can't have" when we talk about a past action. For instance, I heard someone knock on the door.It can't have been our neighbour. Thank you.

Hello GIRIKUMAR,

While could can function as the past form of can when describing ability (I can swim vs I could swim), here you are using them for (im)possibility. In this use, they are interchangeable in many contexts. However, can't have is generally used for more recent contexts and couldn't have for ones further back in time.

You can read more about this in the discussion on this page:

https://english.stackexchange.com/questions/141589/cant-have-been-vs-couldnt-have-been

Peter

The LearnEnglish Team

I don't think I will be wanting for any better explanation than that of yours. Thank u so much, sir.

Dear Sir, Kindly tell me the exact meaning of the following sentence. I personally feel that it has two meanings 1) Anyway he came here yesterday. 2) He had the possibility to come here yesterday, but he didn't come. I would like to know whether my understanding is correct. Kindly advise me on this. 1) He could come here yesterday. Thank you.

Hello Aniyanmon,

The sentence does not look correct to me. You could say either of these:

He could have come here yesterday. [it was possible but he did not come]

He was able to come here yesterday. [it was possible and it is not clear if he came or not]

He could come here yesterday is incorrect because it implies some kind of time travel: a present or future possibility (He could come here) with a past event (yesterday).

Peter

The LearnEnglish Team

Thanks a lot sir.

Hi all, I have a question. Is it possible to use "could not be able to" in any context? Thanks in advance.

Hello japezuela,

I think would not be able to... is far more likely in any context I can think of. Did you have a particular context in mind?

Peter

The LearnEnglish Team

Hi Peter, Thanks for answering. I was thinking of, for example, in a situation in which it was too difficult for me, or out of the question, to be able to. Could I say, ' I could not be able to play a piano' referring to a past situation meaning " it was too hard for me playing the piano because I didn't have the necessary skills for doing so? Thanks in advance.

Hi japazuela,

In that situation we would use either 'able to' or 'could', but not both together:

I could not play the piano.

I was not able to play the piano.

The only time we might use 'could' and 'able to' together is when we are using 'could' to talk about possibility rather than ability. In other words, 'could not be able to' might mean 'it is possible that [he/she] would not be able to...'

However, it is hard to think of a situation where we would use such a form, and I think other less ambiguous forms would be preferred in any case, such as 'could be unable to', 'might not be able to' or 'might lose the ability to'.

Peter

The LearnEnglish Team

Need your help in vetting the below statement for grammatical mistake 'Does AMS can lead to death? ' Pls.check & help me with corrections.

Hello gullu_summi

No, I'm afraid that's not correct. 'can' is a modal auxiliary verb and so 'do' is not used in a question. The correctly formed question would be 'Can AMS lead to death?'. I'd suggest you read our Question forms page for more on this grammar.

All the best

Kirk

The LearnEnglish Team

Hi could you please help me, what to write(can or could) in the following sentence. 'I am very hungry. I can/could eat a horse'. What's the correct answer?

Hello Garry301,

The correct form is 'could' because you are talking about a hypothetical situation (I could eat a horse if you gave me one) rather than a physical ability (I can eat a horse because I've got an enormous stomach).

Peter

The LearnEnglish Team

if she is single today, i could have married her. Am i correct? means - the ga if this gal is unmarried , i can mry

Hello Ali. Chy

No, I'm afraid that's not correct. I'm not completely sure what you want to say, but 'If she is single, I could marry her' is grammatically correct and logical.

All the best

Kirk

The LearnEnglish Team

What would be the correct way of asking a teacher to meet me the next day? 1. May I meet you tomorrow, please? 2. Could we meet tomorrow, please? 3. May we meet tomorrow, please?

Hello Sheena virmani

Those are all fine, but I would recommend 2 -- it's probably the most common way to phrase a request like this. Or if you want to be more formal, 1 is more appropriate.

All the best

Kirk

The LearnEnglish Team

Hello, Could you please guys open the questions and answers for will and would topic . we're a group of students and we would like just to review them and won't ask any questions please.

Hello Hayder991 Thanks for your comment. We recently updated that page and must have inadvertently turned off the comments. I've just fixed this, so you and other people can now make comments on that page. Thanks for letting us know! All the best Kirk The LearnEnglish Team

Sir, I want to ask what form of tense should we use in this sentence with could? "He was Martyred in prostration because no one could 'Killed' him in battle"

Hello Taqi, The correct form here is the base form: '...no-one could kill him in battle.' ~ Peter The LearnEnglish Team

Hello Team! I have a question. ''All test, whether final, in-process, or for information, shall be performed to a Buyer-accepted procedure and shall be documented. As appropriate, the UT records for examinations other than the final should so state.'' In this sentence,why is verb "state" used after "so"?I think verb has to follow modal verb. Does "should so state" here mean "documented"? Thank you so much!

Hello Goktug123 'so' means 'this' here (it can also mean 'in this way') -- another way of saying this (less formal) is 'should state (or 'indicate') this'. I can appreciate that you are trying to understand the English language that you encounter in your life and work, and we're happy to help you with this from time to time, but please remember that in principle we don't explain language that comes from other sources, and certainly not routinely. All the best Kirk The LearnEnglish Team

Dear sirs, although I have been trying to find out if I can use "Can ...?" question form to ask about possibility, I was not able to arrive at a conclusion if it could be used in some kinds of statements. It seems it can always be used specifically if the verb is a stative one (as in "Can he know George?" and not if the verb is a dynamic one (as in "Can it rain tomorrow?"). Again, it seems that we can use it only in the present progressive denoting "now" (as in "Can he be having a bath at this time of day,") but not in a present progressive statement denoting future (as in that personal arrangement question, "Can they be meeting tomorrow?" I figured these out, not based any information, but by examining the examples I came across on the web? I am not sure if I am right. Will you please illuminate me about the matter? Thank you in advance. Best regards.

Hello arthurlocke,

I think it's perfectly fine to use 'can' in all of those situations in terms of grammar. The reason some examples seem less convincing is, I think, rather the result of it being difficult to imagine an appropriate context rather than a grammatical issue. For example, all of these sentences are perfectly fine:

Can it rain on Mars, or is it too cold and dry?

Can the match really be happening tomorrow? There's a transport strike, it would be ridiculous!

Peter

The LearnEnglish Team

Dear sir, do you mean we can say "Can it rain tomorrow?" / "Can they be meeting tomorrow?". I wanted to know if "can" behave differently when used with dynamic vs stative verbs and with present continuous vs future present form of the present simple. As far as I understand, "Can he be having a bath at this time of day?" is true but "Can they be meeting tomorrow?" is wrong. Am I right? If I am, will you please let me know the differences between the questions. If I am not right, will you please recommend me a few sources that could let me understand the uses of modal verbs thoroughly. Thank you in advance.

Hello arthurlocke,

As I said in my earlier reply, there is no grammatical problem with using 'can' in these ways. Provided the context is appropriate, you can use 'can' with both simple and continuous infinitive forms:

After so many arguments, can they be meeting tomorrow?

As far as I know, she is still in Japan and he is in London. Can they be meeting tomorrow?

Can they be meeting tomorrow? Four members of the board are sick, so I don't see how there can be a quorum.

The British Council does not recommend publications as we have a policy of neutrality with regard to publishers. As far as resources go, other than this section on our site, there are many grammar books available from the major publishers. The best way to choose is to visit a good bookshop and take a look at several grammar books so you can compare entries on the same topic to see their levels of detail and clarity of explanation side by side.

Peter

The LearnEnglish Team

So, what goes in "She could help if she _____.(can,could)"?

Hello Ashmin,

I'm afraid neither answer sounds right to me. Perhaps 'She would help if she could'?

All the best,
Kirk
The LearnEnglish Team

Dear sirs, I have read somewhere that we can use "may / might have done" even when we are talking about the future. There were no examples given. If the information is correct, will you be kind enough to explain and examplify it. I would be grateful if you would also tell me if the case for "could have done" is the same or not. Thank you in advance.

Hello arthurlocke,

It is possible to use perfect modal verbs with a future meaning provided you have a future point in time from which you are looking back. The so-called future perfect form (will have done) is an example of this bith other modal verbs can be used in place of will, so long as the context is suitable. For example:

We will have finished it by Thursday. That's a promise!

We might have finished it by Thursday, but that's impossible now.

We could have finished it by Thursday, if not for your mistake.

Peter

The LearnEnglish Team

Sir.. What is difference between two sentence "They could arrived now" "They could have arrived know"

Hello dhana,

Neither sentence is correct.

In the second sentence the last word should be, I guess, 'now' rather than 'know''. In this sentence the speaker is speculating about the present. They are guessing that the people ('they') are probably already at their destination.

The first sentence is not correct. We do not use a past form after 'could', so you cannot say 'could arrived'.

Peter

The LearnEnglish Team

Hi, learnenglish! I would like to ask a question regarding "can/could". I had an essay assignment, and in that essay, I wrote "Everyone in my family counted on television, either for keeping on top of news or for entertainment. In addition, I also could not forget the joy when I watched morning cartoons." But, my teacher revised it and she told me that it should be "In addition, I also cannot forget" instead of "could not forget". My question is, why "I cannot forget" is the correct answer where in fact I talked about something in the past. Thank you for replies.

Hi araisin,

If possible, you should ask your teacher, but I imagine she was thinking that the action of remembering (not forgetting) is in the present time. In other words, the things that you remember are in the past, but the action of remembering them is in the present. Does that make sense?

All the best,
Kirk
The LearnEnglish Team

Dear Can we write “Jimmy can play the guitar well and jumps the farthest.” Although the correct answer is “Jimmy can play the guitar well and jump the farthest.” Thank you

Hello tjmanya,

Yes, that is possible, since the verb 'jump' can be used without the modal verb 'can' or with it. In other words, in your version, 'jumps' is not modified by 'can'. Most of the time, however, people say 'can jump the farthest' instead of 'jumps the farthest', so I'd recommend using 'can' with it.

All the best,
Kirk
The LearnEnglish Team

hello sir. im just?? confused as to which is correct between "what more could i ever ask for" and "what more can i ever ask for" or both can/could apply to the sentence?

Hello ksjksyhmwwjh,

It's difficult to be clear without having a context to which we can refer. In general, we use 'could' when the situation we are describing is either (a) a real situation in the past (the speaker may be talking about his or her childhood, for example) or (b) a hypothetical or unreal situation in the present or future. We use 'can' when the situation is a real or likely situation in the present or future.

Best wishes,

Peter

The LearnEnglish Team

hello again sir. if i were to use it in this sentence: "I'm blessed with good family, good friends and good health. What more can/could I ask for in life?" which one should i use?

Hello

In this case I think 'could' is probably the best option. 'Can' suggests that asking for more is a real possibility, while 'could' suggests that it is purely a hypothetical situation. Perhaps a very religious person who is praying and who believes that they are speaking to their god might say 'can', for example, but generally 'could' is the more natural-sounding option.

Best wishes,

Peter

The LearnEnglish Team