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=

 

Comments

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

All the previous questions and answers have disappeared . we just wanted to go over them before our exam . that's so frustrating , anyway thank you.

Hello Hayder991
I'm sorry about that. If you want to ask any questions, please don't hesitate. The explanation on the new page is more complete. I'd also recommend the Talking about the future page (https://learnenglish.britishcouncil.org/english-grammar-reference/talkin...). Many of the forms on that page are not 'will', but often people study them at the some time.
Good luck to all of you on your exam!
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.

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