'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



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Hello monnzz,

The sentences need a little addition:

(1) 'I don't know if that could have been John.'


(2) 'I don't know if that could be John.'

(1) is about the past: we are considering (doubting) if it was possible for what we saw to be John, perhaps because it did not look like him, perhaps because John is on holiday etc.

(2) is actually about the present: we would usually use this when we can still see the evidence, such as a photo from the night before, and are discussing it.

An alternative would be to use a past simple form, and I think this is probably the most natural way to say it: I don't know if it was John.

I hope that clarifies it for you.

Best wishes,



The LearnEnglish Team

First of all I'd like to thank you for your answer.

Unfortunately, not exactly:(

One more example would be much appreciated:)

1) It could have rained. 

2) it could rain.

I'd like to underline we are still talking about the past possibility.

So 1) means,we don't know if it rained or not, but from what we can see now (things are wet, for example) it is one possibility.' (I stole your words here from topic below, sorry, but this example is great:))

But what about the second one? What does it mean?

Sorry for bothering you:(

P.S.  In your answer i noticed an interesting usage of 'would'. (we would usually use this when we can still see the evidence). But couldn't  you just say 'we usually use...'. 

So far I know that we can use 'would' for the second conditional, somebody's opinion, presumption, polite requests, uncertainty or past form of will.

But i wouldn't say that even one of my row suits your usage.

Or is it the second conditional, and you imply that if we used 'could' we would use it for 'here goes some explanation'. But at that moment when it was present time we didn't use 'could' so it was impossible?

Thanks in advance, Mike

Hello Mike,

As far as the use of 'would' goes, it's a use of the modal to show typical behaviour, with a similar meaning to 'we (would/will) usually choose to'.

Your example of 'It could rain' here does not appear to me to be about past possibility.  As I said in my previous answer, it appears to be (speculation) about the present.  Perhaps you could provide the context for this sentence, because at the moment it does not appear to be about the past at all.

Best wishes,



The LearnEnglish Team

Submitted by kristina26 on Sat, 29/06/2013 - 07:21


Could you explain what's  different between "may have" and "might have", "can have" and "could have"? All of them are used in the past

Submitted by chrisf on Sat, 22/06/2013 - 05:30


Hi there,

I am not quite sure the meaning of "could" in the following sentence taken from the words of a song.

You have built your wall so high that no one could climb it but I am gonna try. 

Does the word "could" mean "would be able to" or "could" in the past?

Thanks for your help in advance.



Hi chrisf,

The tenses in this sentence are a little inconsistent.  In standard English, we'd be likely to say either 'You built [past simple]... could climb...' or 'You have built [present perfect]... can climb...'  However, songs are a form of poetry and poetry breaks all kinds of rules, so it's not really a good idea to analyse the grammar too much.  Just enjoy the song!

Best wishes,



The LearnEnglish Team

Submitted by Mohanad0002220 on Mon, 20/05/2013 - 14:18




till now i cant understand what is the difference in the meaning between the following

in the past, you could lose your way in the dark

in the past, you could have lost your way in the dark


is the following explanation true:

for the fist one, it means there was a pliability to lose your way in the past

for the second one, it means there was a possibility to lose your way in the past but you didn't lose it


thanks in advance

Hi mohanad0002220,

A good question - thank you!  Modal verbs have many different meanings, and could have is no exception: it can be used for ability, possibility and for logical deduction, for example.

When we talk about what possibility, we usually use 'could have' to talk about things that were possible but didn't happen, and 'could' to talk about things that were possible (and may or may not have happened), so what you say is correct.  Well done!

However, the sentence could also mean something different if you are talking about logical deduction, for example:

'You could have lost your way in the dark' = 'We don't know what happened, this is one possible explanation'.

This means that a simple sentence can have several possible meanings.  For example:

'It could have rained this morning' could mean...

'It looked like rain, but in the end it didn't rain.'


'We don't know if it rained or not, but from what we can see now (things are wet, for example) it is one possibility.'

As you can see, it's very much dependent on the context and the speaker's intention.  That's what makes modals so tricky, and so wonderfully useful!

Best wishes,


The LearnEnglish Team

Submitted by sadakat15 on Tue, 16/04/2013 - 09:44


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?

Submitted by Ebenezer Son on Sat, 13/04/2013 - 10:52

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? Thanks.

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

Submitted by Ebenezer Son on Sat, 13/04/2013 - 10:37

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

Submitted by Ebenezer Son on Sat, 13/04/2013 - 10:22

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. Thanks.

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

Submitted by Ebenezer Son on Sat, 13/04/2013 - 10:01

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. Thanks.

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

Submitted by zuzana83 on Sun, 10/02/2013 - 13:58



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... 


Hello Zuzana,

Glad to hear you found this section useful. Modals are confusing, but they are important and I think that a good understanding of them can really help learners with their English.

Best wishes,


The LearnEnglish Team

Submitted by Bebby Untag on Fri, 08/02/2013 - 03:28


Hey! Help me with British and American English please! Do any two word verbs like Wear off, put on, think over, and etc have same meanings in British and American English? I'm just worried about having wrong comprehension of the two word verbs.

Hello Bebby!

Most have similar meanings. A few may be different, but a good dictionary will tell you when there is a problem. I certainly can't think of any where your meaning would be confusing for British or American speakers.

Hope that helps!




Jeremy Bee

The LearnEnglish Team


Submitted by hsm hunsy on Fri, 09/11/2012 - 10:10


Dear All friend

all friend can help me when we use can when we use could when we use be able to i'm from cambodai i hope all friend can help me!!!

Hello hsm hunsy!


Welcome to LearnEnglish! In answer to your question, there are two areas where we use be able to rather than can or could.


The first is to do with grammar. There is no v-ing, (xxxcanning swim is useful ), no infinitive (xxxI want to can swim), no future form (xxxI will can swim when I finish the lessons) or past participle (xxxI have can to swim since I was 7). In all these situations, we use be able to:

  • Being able to swim is useful.
  • I want to be able to swim.
  • I will be able to swim when I finish the lessons.
  • I have been able  to swim since I was 7.

We use could as the past of can, though: I could swim when I was 5.

The second time we use be able to is when we are talking about a single, special time, when we did something:

I lost my house keys. Luckily, I was able to climb in the window. (Not - I could climb through the window)

Hope that helps!


Jeremy Bee

The LearnEnglish Team


Submitted by Alchemist on Sat, 13/10/2012 - 02:44


Hello There,

                     My question to you all is,can we use the modal  CAN and the adjective ABLE together in a sentence? Example: I can able to do five tasks at a time !

Submitted by Jeremy Bee on Tue, 20/11/2012 - 04:07

In reply to by Alchemist


Hello Alchemist!


The short answer is - no, you can't! You don't put adjectives after can, and what do you think can able would mean, anyway?

If you use can/could to show possibility, then the following is OK:

I could be able to finish it by the end of the week if I work hard on it.

But you still need be!

Hope that helps,


Jeremy Bee

The LearnEnglish Team

Submitted by Ajit Vyas on Sat, 06/10/2012 - 14:02


hello  good day.

I have one question should i start from  tense or  general topic ?

for improving english.

thsnks in andvance


Submitted by surfinia_purple on Sat, 15/09/2012 - 09:18


100%,i got.................

Submitted by Salehthegreat on Tue, 11/09/2012 - 19:04


it's really helpful. i am learning a lot and hopefully it help me in future.

Submitted by Fur4eng on Sun, 26/08/2012 - 13:42



I just want to make sure if the question 5 of this exercise is grammatically correct?

Hello Fur4eng!


You're absolutely right - there was a mistake in the exercise. I have corrected it now; thanks for pointing it out! Let us know if you spot anything else, and enjoy the rest of the site.





The LearnEnglish Team

Submitted by vishnoiprem on Sun, 19/08/2012 - 16:27



This is  very useful for me.

Submitted by Satish Pathak on Mon, 04/06/2012 - 18:19


It"s really interesting site ..... i searched that site for last 2 year...

Submitted by Charina on Mon, 14/05/2012 - 10:08


Hi! This is a very interesting site.

I would like to know if it's possible to use "could" and be able to" together.

Is it okay to say "I could be able to do that."

Thank you very much!

Submitted by fatima hussain on Wed, 28/03/2012 - 11:21


hi everyone  I'm very happy to use this website and I must say it could help you what you want to learn

Submitted by valiumarao on Wed, 29/02/2012 - 06:25


Very good learning with respect to usage of can,could in different situations.

Submitted by Lisa.R on Thu, 26/01/2012 - 13:18


Hello everybody,

Just a quick question

In the example above there is this sentence: 'If we don’t hurry we could be late'.

Can't you say 'if we don't hurry we are going to be late'? It seems more natural to me...



Thank you for such a brilliant question.Stephen Jones' reply to your query has cleared my confusion as regards the better choice between the two sentences.