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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




Hi kamrina,

Are these sentences supposed to be questions? If so, they should be:

Can we celebrate our birthdays together?
Could we celebrate our birthdays together?

Both of these questions are correctly formed. The one with could is more polite or formal than the one with can, but they have the same meaning.

Best wishes,

The LearnEnglish Team

What form of the verb are used with 'can be'? Can we use 1st form of verb with can be?

Hi vikramkbc,
Modal verbs like can are followed by the first form of the verb when speaking about the present.
When you ask about can be, be is the first form of the verb, but you could put the first form of any verb after can, e.g. can speak, can write, etc.
Is this what you were asking about?
Best wishes,
The LearnEnglish Team

Hi sir could you please help with this sentence?I'd be really grateful i mean i just don't know if it's referring to the past or future. The sentence is, we could be doing a lot worse,

Hi Monty,
In this sentence, could be doing is referring to the present, specifically to the idea that it's possible for the present situation to be different now, depending on how things went in the past (see the last explanation under Possibility above).
Best wishes,
The LearnEnglish Team

Hi sir can you help me with this sentence? You couldn't possibly love me as much i do

Hi Monty Stevens,
I'll be happy to help you, but I'm not sure what the problem is!  The sentence is correct, but has a rather odd meaning - it sounds like the speaker is saying that they love themselves more than the other person could, which is rather egotistical to say the least!
Best wishes,
The LearnEnglish Team

Hallo, Peter, thanks for having patience with me and answering my questions:)
what about this example:
here is some background: "Me and some friends went camping and the next morning we discovered that one of our friends missing, so
Our friend could lose his way in the dark.
Our friend could have lost his way in the dark.
Honestly, Im not sure this example is what we need in this particular topic, because i believe i need to use "could have lost" here, because of that is one of explanations why our friend lost his way. (perhaps, he didn't like camping and went home not notifying us)
So is it possible to remake this situation somehow so we could use "could lose" instead? 
P.S. So we can use "would" to show typical behaviour such as, for example:
I would usually go for a walk in the evening.
(But could i just say: I usually go for a walk in the evening?) Does it mean the same? 

Hello monnzz,
In your first example I think 'could have' is necessary.  If we weren't talking about a specific situation but rather indulging in general hypothetical speculation about the possibility of getting lost then 'could' would be possible.
In the example you give 'would' describes a past habit, similar to 'used to', rather than a present habit.  The use of 'would' in my sentence is quite a tricky one, and it usually appears when we contrast characteristic behaviour or choices of different people.  For example:
People in my country like to go for a walk in the morning.
Oh, really?  In my country people would usually go for walks in the evening.
As I said, this use usually carries a meaning of 'would choose/like/prefer/opt for'.
Best wishes,
The LearnEnglish Team

Hello Peter, now I've caught the idea:) Thank you very much for such a good explanation:)