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'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.


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]


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.


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?


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.


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 ...?
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


can and could: possibility 2


can and could: other uses 1


can and could: other uses 2




Or it shows a suggestion here??

Hi Rsb,

Yes, I think it's a suggestion too! It could be a request if it was in the question form: Could you help?

Best wishes,


The LearnEnglish Team

Thanks Jonathan sir!

Hello Kirk,

I have a doubt about the different verb patterns used for the verbs "to recommend", "to suggest" and "to advise" as, depending on the source consulted, some patterns are accepted and some are not.

I will list down only those patterns on which different book texts don't agree (so I am not sure whether they are right or not):


1/ Subject + verb + someone-object + to infinitive

Is this structure RIGHT or should a passive be used instead? Some books say it is not!
Ex: The doctor recommended/suggested him to do exercise (right
or "He was recommended/suggested by the doctor to do exercise" must be used instead??)

Or CAN this pattern be used for "to recommend" but not for "to suggest"??

2/ Subject + verb + (someone or to someone)? + that + ....
Ex: The doctor recommended/suggested (me/to me) that he should do exercise


3/ Subject + verb + that + someone-subject + BASE VERB
Ex: The doctor recommended/suggested/advised that he DO exercise (whether it's present -regulary) or past (those months))
or should it be:
- the doctor recommended/suggested/advised that he does exercise (regularly) - if it's present ("haga")
- the doctor recommended/suggested/advised that he did exercise (those months) - if it's past ("hiciera/hiciese")

Thanks for helping me to clarify this.

PS. And happy new year ;-)!

Hello Gloria,

I'm not in a position to say that other text books are wrong, but I can tell you what I understand to be correct.

I would not use pattern 1 with 'recommend', but in at least one of my reference books, it is listed as correct, so I would go with that. Neither I nor my reference book consider pattern 1 correct with 'suggest'. In general, I would avoid the passive here, even though it might be grammatically correct in some cases.

I'm not sure if pattern 2 is incorrect or not, but I'd recommend avoiding it. If it's really necessary to specify that the advice for another person was given to a different person, I'd use a couple of sentences to explain that.

As for pattern 3, as far as I understand it, only 'do' is really correct here. This is an example of the subjunctive, which is far less developed in English than in Spanish; in this case, 'do' is a translation of both 'haga' and 'hiciera/hiciese' and so you'd need some other phrase (or the context) to make it clear if the recommendation is speaking about the present/future or the past.

I should mention that most native speakers of English don't know what the subjunctive is, and so you might find them using 'does' or 'did' where I've said you should use 'do'. I believe most editors, though, would recommend 'do' here.

Hope that helps. Happy New Year to you too!

All the best,


The LearnEnglish Team

I'm still confused about general & specific ability

Hi Stellaaa,

You can use 'can' to speak about someone's ability to do something in general ('She can swim'), and you can also use it to speak about how they manage to do something in a specific situation ('I can help you now').

You can use 'could' to speak about someone's ability in the past ('My grandmother could speak Swedish') but not to speak about how they managed to do something in a specific situation (not 'The fire brigade could rescue the child', instead: 'The fire brigade was able to rescue the child').

All the best,


The LearnEnglish Team

Hi team,
"He couldn't be a basketball player.He isn't tall enough.''Teacher in this sentence I think - could- use for probability because" He isn't tall enough."Present simple.But In my book says - could- use for ability. Which one is right?I think mine.

Hello Yigido,

All of the modal verbs have several different meanings and uses. In this case, it sounds to me as if 'couldn't' is speaking about a hypothetical situation: if he wanted to be a basketball player, he could not be one because he isn't tall enough.

Does that make sense?

All the best,


The LearnEnglish Team

Actually teacher sentences are ''He__be a basketball player. He isn't tall enough.''Answer key says couldn't.
I mean it does not say about which meaning.I am still confused If ıt was hypothetical situation,why wouldn't sentences like that?