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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.

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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Comments

Hi Lucas_xpp,

In your first sentence, could is used to show possibility. You could replace it with may or might but not with can, which would show ability, not possibility.

 

In your second example, could is used to show past ability. You could use can here, but it would change the meaning to present ability. Given that the situation is still unresolved, can works fine here.

 

In your third example, you could use would. Both could and would can be used in this type of polite request.

 

Peter

The LearnEnglish Team

We could not pause the job losses indefinitely — it was always a question of ‘not if, but when’

This is an announcement by a company of job cuts. Why is "could" used instead of "can"?

in every sense of the word means In every way in which something could be interpreted or understood.

Why is "could" used instead of "can"?

Thanks a lot teachers.

Hi Anisha00329,

In the first sentence, could not shows inability in the past. You might argue that the situation (cutting jobs) is a present situation, not a past one. But by using the past form could not, the speaker frames it as a past action. It may be referring to the time that the job cuts were decided (which is a time before the current announcement, i.e. a past time).

 

In the second sentence, could is used to show hypothetical possibilities, not real ones. It's not claiming that this thing actually is or can be interpreted or understood in all these ways in reality.

 

Best wishes,

Jonathan

The LearnEnglish Team

1) This was the best room we could get at such short notice. - Would it be better to say "we were able to get"?

2) A course is an action or series of actions that you could take in order to deal with a particular situation - Would it be better to say "you can take"?

3) the question for the next six months is the extent to which those countries opposed to the world being divided can prevail - Since this refers to a future event, why is "can" used instead of "could"?

Thanks a lot English Team.

Hi AsahiYo20,

I'll try to answer your questions in turn.

  1. Both could and were able to are possible in this sentence. Were able to is often used to show ability on a particular occasion (see here for more explanation and examples). But That was the best I could do (and variations) is a very common phrase too.
  2. You can use can or could, but the meaning is slightly different. Can presents 'taking action' as a realistic possibility for the listener. Could presents it as an imagined or hypothetical situation.
  3. We can use can to talk about the ability to do something at a future time. For example: I can go on holiday next month.

Does that make sense?

Best wishes,

Jonathan

The LearnEnglish Team

You gave everything you can throughout.
Is it a complusion that "could" should be used instead of using "can"
Would be really grateful if someone responds to the query.
Thank you :)

Hello Sharath.v,

It's hard to be absulutely certain without knowing the context, but I think could is necessary here because the whole sentence is in the past, as shown by the past tense verb gave.

 

Peter

The LearnEnglish Team

1) He couldn’t be a doctor. He isn’t wearing a white coat

This sentence seems to be about present impossibility. I think only "cannot" can be used to express such meaning. But why is "couldn't" used here instead?

2) It might/could be described as an act of provocation.

Could I use may/can instead?

Grateful if you could help.

Hello Najmiii3579,

Your first sentence looks rather odd to me. I think the normal form would be either [can't be > isn't wearing] for present meaning or [couldn't be > wasn't wearing] for past.

 

With your second sentence, it's difficult to say for sure without knowing the context and intention of the speaker. A word might be possible in theory, but change the meaning in such a way that it is highly unlikely, and we would have to describe each context in detail to explain.

If you can tell us what you want to say (i.e. what meaning you want to convey) then we'll be happy to help you to do so.

 

Peter

The LearnEnglish Team

Sir,

I have two questions. Grateful if you could help.

1st Sentence: "He has every attribute you could want and could play for any team." Could I use "may" or "can" instead of can?

2nd Sentence: "The earliest we can finish is next Friday." Could I use "can" or "may" instead?

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