Possibility

We use the modal can to make general statements about what is possible:

It can be very cold in winter. (= It is sometimes very cold in winter)
You can easily lose your way in the dark. (= People often lose their way in the dark)

We use could as the past tense of can:

It could be very cold in winter. (=Sometimes it was very cold in winter.)
You could lose your way in the dark. (=People often lost their way in the dark)

We use could to show that something is possible in the future, but not certain:

If we don’t hurry we could be late. (=Perhaps/Maybe we will be late)

We use could have to show that something is/was possible now or at some time in the past:

It’s ten o’clock. They could have arrived now.
They could have arrived hours ago.

Impossibility:

We use the negative can’t or cannot to show that something is impossible:

That can’t be true.
You cannot be serious.

We use couldn’t/could not to talk about the past:

We knew it could not be true.
He was obviously joking. He could not be serious.

Ability:

We use can 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 to talk about the ability to do something at a given time in the present or future:

You can make a lot of money if you are lucky.
Help. I can’t breathe.
They can run but they can’t hide.

We use could to talk about past time:

She could speak several languages.
They couldn’t dance very well.

 

Permission:

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 if you like.
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 free.

Instructions and requests:

We use could you and 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 and invitations:

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 can give you a lift to the station.

 

Exercise

Comments

So, what goes in "She could help if she _____.(can,could)"?

Hello Ashmin,

I'm afraid neither answer sounds right to me. Perhaps 'She would help if she could'?

All the best,
Kirk
The LearnEnglish Team

Dear sirs,

I have read somewhere that we can use "may / might have done" even when we are talking about the future. There were no examples given. If the information is correct, will you be kind enough to explain and examplify it. I would be grateful if you would also tell me if the case for "could have done" is the same or not. Thank you in advance.

Hello arthurlocke,

It is possible to use perfect modal verbs with a future meaning provided you have a future point in time from which you are looking back. The so-called future perfect form (will have done) is an example of this bith other modal verbs can be used in place of will, so long as the context is suitable. For example:

We will have finished it by Thursday. That's a promise!

We might have finished it by Thursday, but that's impossible now.

We could have finished it by Thursday, if not for your mistake.

 

Peter

The LearnEnglish Team

Sir..
What is difference between two sentence
"They could arrived now"
"They could have arrived know"

Hello dhana,

Neither sentence is correct.

In the second sentence the last word should be, I guess, 'now' rather than 'know''. In this sentence the speaker is speculating about the present. They are guessing that the people ('they') are probably already at their destination.

The first sentence is not correct. We do not use a past form after 'could', so you cannot say 'could arrived'.

 

Peter

The LearnEnglish Team

Hi, learnenglish!

I would like to ask a question regarding "can/could".
I had an essay assignment, and in that essay, I wrote "Everyone in my family counted on television, either for keeping on top of news or for entertainment. In addition, I also could not forget the joy when I watched morning cartoons."

But, my teacher revised it and she told me that it should be "In addition, I also cannot forget" instead of "could not forget".

My question is, why "I cannot forget" is the correct answer where in fact I talked about something in the past.

Thank you for replies.

Hi araisin,

If possible, you should ask your teacher, but I imagine she was thinking that the action of remembering (not forgetting) is in the present time. In other words, the things that you remember are in the past, but the action of remembering them is in the present. Does that make sense?

All the best,
Kirk
The LearnEnglish Team

Thank you so much Kirk for the answer :)
It helps me a lot.

Dear
Can we write “Jimmy can play the guitar well and jumps the farthest.” Although the correct answer is “Jimmy can play the guitar well and jump the farthest.”
Thank you

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