'can' and 'could'

a swimmer in the swimming pool

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

Matching_MTYzNjk=

can and could: other uses 2

GapFillTyping_MTYzNzA=

 

Average
Average: 4 (70 votes)
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Submitted by whitekrystal on Sun, 17/12/2023 - 13:47

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Why is "could" used rather than "can" in this setence?

Aston Villa could move top of the Premier League if results go their way today

Hi whitekrystal,

Using "could" suggests that the speaker sees this as less certain or less likely to happen than with using "can". 

Jonathan

LearnEnglish team

Submitted by Gendeng on Tue, 12/12/2023 - 17:40

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I read comments here and found "could" in "you could use...". What's the meaing of "could" in this sentence? Is it a possibility or hypothetical? I'm confused. You quite often say "you could say/use, etc" in your comments.

Would here is used to suggest a hypothetical alternative. You can imagine an implied if-clause: "if you wanted to use a different word."

You could use a simple present form instead: Alternatives to kiss are...

Hello Gendeng,

In 'You could use a present simple form instead', 'could' expresses a hypothetical situation. It is a situation that doesn't exist right now; it is a situation one can imagine existing.

What exactly the word 'possibility' means can be confusing. In the explanations in our English grammar reference, when we say something is 'possible', we typically mean that it is not certain. (In general usage, though, 'possible' has lots of other meanings.) For example, the sentence 'John could be at home' expresses possibility: maybe John is at home (but we don't know for sure). But this meaning is not the meaning expressed in 'You could use a present simple form instead'.

'could' can also mean 'would be able to' or 'it would be possible to' (though not here 'possible' doesn't talk about probability; it talks about a situation one can imagine existing). This is how we use 'could' in a sentence like 'You could use a present simple form instead'. So we can rephrase 'You could use a present simple form instead' as 'It would also be correct to use a present simple form instead'.

There are many other uses of 'could', but I hope the distinction I'm trying to explain here helps you.

Best wishes,
Kirk
LearnEnglish team

Thanks Kirk. If it's a hypothetical, the sentence usually contains some sort of an "if" clause. But there is not. Could you explain why?

Hello Gendeng,

When we think the context makes it clear that we're discussing a hypothetical, we sometimes leave out 'if' clauses.

In the context of our responses to users in the comments, we're often talking about how users could use language in hypothetical situations, which is why we use these forms so much. Though they are also very common in other contexts as well.

Best wishes,
Kirk
LearnEnglish team

Submitted by Nyenok on Wed, 06/12/2023 - 03:43

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"Can" and "could" can be used for a possibility. What is the difference?

Anyone can make a mistake.
Anyone could make a mistake.

Anyone can become President.
Anyone could become President.

Hello Nyenok,

As the page says, can is used for general statements about possibility while could is more specific. In your examples, the first sentence is a general statement about people and/or society, while the second would be more likely when talking about a particular group of people. Of course, this would be clarified by the context in which the sentences are used.

 

Peter

The LearnEnglish Team

I want to understand the difference. Could you give context so that's clear for me?

Hello Nyenok,

Please have a look at the Cambridge Dictionary Grammar's page on can, could or may?. I think you should find that helpful.

We're happy to help you understand, but we ask that you explain to us what you understand and that you explain possible contexts to us. That will give an insight into what you understand and what you do not, which will help us help you.

Best wishes,
Kirk
LearnEnglish team

Submitted by Anastasia I on Fri, 03/11/2023 - 21:36

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Hello! Could you please clarify whether 'could' or 'can' should be used in the sentences below, and why?
1. Alex could be pretty straightforward when he expresses his thoughts. Even if he’s going to say something unpleasant, he never tries to make it sound nicer.

2. Alex can be pretty straightforward when he expresses his thoughts. Even if he’s going to say something unpleasant, he never tries to make it sound nicer.

Thank you!

Hi Anastasia I,

Sentence 2 is the right one. I think the idea is that Alex has this particular ability (of speaking in a straightforward way). "Can" is used to show an ability in the present. "Could" is only used for an ability when it was in the past.

I hope that helps.

Jonathan

LearnEnglish team

Hi Anastasia I,

If the idea is possibility, then both "can" and "could" are correct. There is a difference in meaning, though.

"Can" is used for general statements about what is possible. This seems the right meaning for your sentence, since the idea of "when he expresses his thoughts" seems to mean "every time ..." (i.e., a general statement), and the following sentence in the present simple (e.g. "he never tries ...") also indicates something that is factual and true generally.

"Could" is used for less general and more specific possibilities. For example, "Be aware when you talk to Alex later that he could be pretty straightforward about the issue" (referring to this particular occasion of talking to Alex).

I hope that helps.

Jonathan

LearnEnglish team

Hello sir , What about : “I made sure that I got to the exam room early so I could sit at the back.” Does could here express ability or possibility? Thank you

Hello aymengan,

Here could describes ability. One way to test this is to see if you can replace it with be able to. If you can, then you are talking about ability. If not, or if the meaning of the sentence changes when you do so, then you must be talking about possibility. In your example you can replace it:

I made sure that I got to the exam room early so I was able to sit at the back.

 

Peter

The LearnEnglish Team

Submitted by annie_po on Thu, 28/09/2023 - 13:59

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Hello, thank you very much for interesting and well-organised information.

I have a question concerning negative questions.
We usually use 'could' in order to ask smb to do smth in a polite way. For instance, 'Could you tell me where the nearest bus station is?'
If we add a negation here (Couldn't you tell me where the bus station is?), how does the meaning change? Is it now about expressing our surprise about the fact that the person we're talking to is not able\doesn't want to answer our question?
And what about the differences between these two questions:
Could you pass me the salt?
Couldn't you pass me the salt?

Thank you in advance.

Hello annie_po,

Very often the meaning of 'couldn't' would be what you describe, but as always, it would depend a lot on the situation.

Out of context, I'd guess that 'Couldn't you pass me the salt?' showed disbelief that a person refused to pass the salt, or it could be a second request for them to do so.

All the best,
Kirk
LearnEnglish team

Hello Prakash,

The 'to help' construction here is not related to the use of 'could'. Rather, it is an infinitive of purpose explaining the reason for the action. The sentence is fine without it:

I did all I could (to help).

You can use this construction with other verbs:

I came here to talk to you.

She quit her job to look after her sick brother.

In your example the verb following 'could' (the main verb for which could is an auxiliary) would be 'do', but it is omitted for reasons of style:

I did all I could do (to help).

 

Peter

The LearnEnglish Team

Submitted by jitu_jaga on Tue, 01/08/2023 - 04:03

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Hello Teachers,
The prince spoke to the princess: “You see, I am not what I seemed to be! I am a prince. A wicked witch cast a spell on me and turned me into a frog.
No one but you could undo that spell, Princess. I waited and waited by the well in the hope that you would help me.”
We use could for past ability. But for a specific event in the past we use was/were able to or managed to.
Then why the author has written in the above para " No one but you could undo that spell". I think it was a specific event in the past and maybe it isn't a conditional sentence. Please make it clear...

Hello jitu_jaga,

Could here is about general ability, not a specific action. When the prince says 'No-one but you could...' he means 'no-one else had the ability to...'. He is talking about a special characteristic of the princess, not an action.

You can see the difference if we imagine a new context:

"Thank you for your help," said the prince. "Many people tried, but no-one was able to change me back until you did it with a kiss."

Here the prince is talking about specific attempts and so uses able to.

 

Peter

The LearnEnglish Team

Submitted by Asi_Asi on Mon, 17/07/2023 - 10:22

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Hi there,
A: I could play this game all day.
B: Oh yeah? But I guess we should give someone else a turn soon.

And
A:Welcome! I'm glad you could come.
B: Thanks for inviting me. These gift are for you.

I can't understand in these two conversations what "could" is implying. Could you help me with that please. Thanks in advance.

Hi Asi_Asi,

I could play this game all day: this probably has a hypothetical meaning, similar to a second conditional structure, with some kind of implied if-clause, e.g. I could play this game all day if it were possible / if I had time (etc.). It doesn't mean that the speaker can actually play this game all day. Instead, it's probably an exaggeration, in order to show how much the speaker enjoys playing the game, and that he/she wants to play it longer (but not literally all day).

I'm glad you could come: this is the past "ability" meaning of "could". The past form is needed because "come" refers to the journey to reach this place, a journey which ended when they arrived.

I hope that helps to understand it.

Jonathan

LearnEnglish team

Submitted by cuntur on Wed, 12/07/2023 - 17:31

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Hello Teachers, I have one question.
"Are you looking for people who manages a good level of English or a low level could be accepted?"
I'm not sure about ".... or a low level could be accepted?" Should I change anything there? I'm not sure if there is a mistake.
Thank you!!!!!

Hello cuntur,

It's definitely understandable the way it's written. I might suggest saying 'or is a low level acceptable?', though it depends a bit on what this sentence is referring to.

I'd also suggest saying 'people who have a good level' -- 'people' is plural in English, so the verb should also be plural. And we usually say 'have' rather than 'manage'.

All the best,
Kirk
LearnEnglish team

Submitted by jitu_jaga on Tue, 25/04/2023 - 13:36

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Hello teachers,
This is the dumbest exam even a stupid could pass.
In the above sentence, could has been used instead of can. My question is, we use can for present ability and could for present possibility. Then, Can we use could for present ability instead of can as above?. Because I don't think it is a case of present or future possibility. Please confirm.

Hello jitu_jaga,

I understand this sentence to mean that anyone could pass this exam if they took it.

Notice the phrase 'if they took it', which shows that the sentence is considering a possible but unlikely situation.

In this usage, 'could' is a conditional form of 'can' in a second conditional structure. We can't say 'would can'; instead we say 'could'.

Does that make sense?

All the best,
Kirk
LearnEnglish team

Submitted by jitu_jaga on Sun, 26/03/2023 - 06:04

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Hello, l have a question.
Amy to Jack- you are spying on me.
How could you do that to me?
In the above sentence could refers to past or present. Does this sentence mean How were you able to do that to me? Or How can you do that to me?

Hello jitu_jaga,

Modals have multiple uses. Sometimes 'could' describes past ability:

When I was a child I could play the piano.

In this case you can replace 'could' with 'was able to':

When I was a child I was able to play the piano.

 

However, sometimes 'could' describes possibility, and then 'was able to' is not an alternative: The speaker in your example is asking 'How is it possible that you did this?' with the sense of 'I did not believed you were the kind of person who would do this'.

Looking at possible responses may help to clarify:

You're spying on me! How were you able to do this? >>>> I used a small camera.

You're spying on me! How could you do this? >>>> I suppose I'm just not as honest as you thought I was.

 

Peter

The LearnEnglish Team

Submitted by lordstone on Thu, 09/02/2023 - 20:51

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Please i need a little bit education on this. Why is it that you could say "I haven't bought a car'' but you can't say" I couldn't bought a car?

Hi lordstone,

It's because the auxiliary verb "have" should be followed by the past participle form of the verb (e.g. buy --> bought).

"Could" should be followed by the base form of the verb ("buy"), not the past participle.

I hope that helps.

Jonathan

LearnEnglish team

Hello, l have a question.
Amy to Jack- you are spying on me.
How could you do that to me?
In the above sentence could refers to past or present. Does this sentence mean How were you able to do that to me? Or How can you do that to me?

Hello jitu_jaga,

It's more of a hypothetical meaning -- it's as if she were saying 'How could you do that to me if you respected me?'.

All the best,
Kirk
LearnEnglish team

Hello Kirk. I'd like to understand your use of "of" in "It's more of a hypothetical meaning". I usually use "more" without the word "of". What does "of" mean in this case?

Hello Selet,

The word 'meaning' can be both count and uncount. In my sentence, it's a count noun, and so needs to be used with an article because it's singular.

When we use 'more' before an article, we have to use 'of' -- it's not correct to say *'more a hypothetical meaning', instead we say 'more of a hypothetical meaning'.

You can read more about this on the Cambridge Grammar page on 'more'.

Best wishes,
Kirk
LearnEnglish team

I'm still confused about the meaning of "more of" here. Does "of" mean "like" in this case? More of a hypothetical meaning = more like a hypothetical meaning? More of suggestion = more like suggestion.

Hello Selet,

More of in the context means 'closer to', so Kirk is saying it is closer to a hypothetical meaning than a real meaning about past or present.

 

Peter

The LearnEnglish Team

Submitted by Rejane-.' on Tue, 26/07/2022 - 21:55

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I have a question. I know that we can use 'can' to talk about permission in the present like 'I can wear jeans to go to school' meaning I'm allowed to wear jeans to go to school. My question is: is it possible to use could in the negative form, couldn't, to talk about permission in the past like 'when I was a teenager I couldn't wear jeans to go to school' meaning I wasn't allowed to wear jeans to go to school. To me if I use couldn't it gives the idea of hability and not permission. It sounds more natural to use 'be allowed to' in this context. Please correct me if I'm wrong. Thank you.

Hello Rejane,

All modal verbs, including 'can' and 'could', have several meanings and uses. The sentence you ask about could mean you weren't allowed to wear jeans, or it could mean that you were not able to wear jeans (for example, if you didn't have any), or it could probably mean other things. The context would normally make the precise meaning clear or the sentence might just be ambiguous.

By the way, please only post your questions once. As you'll have seen, it takes a little time for your comments to be published and publicly visible, but we will publish them as we can.

All the best,
Kirk
The LearnEnglish Team

Thank you for your answer. As I understand, both, could and couldn't can be used in the past form to mean permission or hability, it will depend on the context. Thank you

Submitted by Faii on Mon, 18/07/2022 - 06:10

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They could/may/might lose the match.
How can we say this in past tense?
We thought they could/may/might have lost the match, but at the end they won.Is it correct ?

Hello Faii,

It's really a perfect form rather than past tense, but your example is fine. If we say 'could have lost' then without any other information we don't know if the match was in fact lost or not. If you add a second clause like the one you have (but...) then it becomes clear what the final result was.

 

Peter

The LearnEnglish Team

Submitted by Faii on Sun, 17/07/2022 - 17:47

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Is it correct to say "He can get here at any time " if we want to mean that there is a strong possibility?

Hi Faii,

If you are talking about one particular occasion (e.g. the person is coming here right now), then I would prefer to use "could" in this sentence for that meaning.

"Can" for possibility is a more general statement. For example, perhaps you are talking about this person's arrival time not on one particular occasion (e.g. today), but as a more general and repeated action (e.g. the time he comes here every day, not just today). So, yes, you can use "can" for that meaning but it gives the idea of a more general action.

I hope that helps.

Jonathan

The LearnEnglish Team