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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




I studied english in Azerbaycan in British consil. İn 12 year ago.But I forget english because nobody of  my friends speaking english.How can you help me?

John confuted their statements and ideas, and impugn on the veracity of their facts.

John refuted their statements and facts, and impugn on the veracity of their of their facts.

Please is CONFUTED and REFUTED interchangeable here? Are they interchangeable in any context at all?


Hello Ebenezer!
If you try our dictionary, you'll see that refuted and confuted are effectively identical in meaning. Confuted is very rare, however, and I would say refuted is the best choice.
Jeremy Bee
The LearnEnglish Team

1. I saw him kick the ball.

2. I saw him kicking the ball.

Please is these two statement the same.

Please could someone help me to understand what is (corollary) in any sentence? By giving me some illustrations?

Thanks for your help

Hello Ebenezer!
These two sentences are very close, but the first one suggests he kicked the ball only once. The second one sounds like he was kicking the ball for a while.

I am not sure what your second question means, I'm afraid. Can you explain a bit more?
Jeremy Bee
The LearnEnglish Team

1. He interupted me before I finished speaking.

2. He interrupted me before I had finished speaking.

A friend explained that number(1) means, the person was interrupted when speaking but he disregarded the words of the interuptor and went ahead to speak.

By number(2) he explained that when the person was speaking and was interupted by the interuptor, he couldnt talked any more. In other words the speaker couldnt go ahead to speak again after the interuption

How true is the difference.


Hello Ebenezer!
Your friend is wrong, I'm afraid. The first sentence uses simple past, while the second uses past perfect. You can read about them on our page about the past tenses.

This question, like your other questions, is not related to this page, which is about can or could. We are happy to answer questions, but please make an effort to find a suitable, relevant page.
Jeremy Bee
The LearnEnglish Team

1. We are happy to see you here.

2. We are happy to seeing you here.

Please what is the main difference between the above two statement.


Hello Ebenezer, again!
The main difference is that the second sentence is wrong. In one of your other questions, you asked about to + verb, which is called the infinitive. Here, the adjective happy is followed by to + verb to give a reason. Take a look at our infinitive grammar page for more information.
Jeremy Bee
The LearnEnglish Team

This is really helpful grammar part. I use also Murphy's English Grammar in Use and Oxford's Practice Grammar. The modals are quite difficult mainly the meaning about opinion of speaker...