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 Teachers, The LearnEnglish Team is very great and thank to you i daily keep improving my English.In order to these clauses above , i noticed some cases in which we can use " should" like in conditional clasues like these ones:1) should you pass by store, please get some bread 2) if you should pass by, say hello to him. another one (subjunctive) for istance: i suggested ironically that the audience should be given the earplugs. i wonder if there are any further cases we can use "should" like above.

i send you my regards.

Hello rosario70,

If you use 'should' in a first conditional sentence, it indicates that you think it's unlikely that the action will happen; in your first sentence, for example, it means you think it unlikely that the person will pass by a store. 'should' is also sometimes used after 'in case' to mean something like 'by chance'. For example, 'I'm going to make a note of our appointment in case I should forget it.'

Keep up the hard work – we're very glad to see you're making progress!

Best wishes,
The LearnEnglish Team

Hello I heard someone saying this I'm her to confirm whether it is right or not In my opinion it is wrong "You have no marketing skills, you cant convince nobody" is it cant or can with nobody OR cant with anybody

Hello Lamastry,

You're right – the sentence you report is not standard English, though there are certainly a fair number of people, including native speakers, who say that. Here you should use 'anybody' instead of 'nobody'. See our indefinite pronouns page for more on this. And by the way, you could find this page yourself by searching for 'anybody' in our Search box.

Best wishes,
The LearnEnglish Team

Thank you sir

what if I want to make a permission letter? Should I write on letter "dear sir, I would ask for your permission that I cannot attend your meeting today"? Or both of the modals are changed to would and could? Thank you

Dear Winson,

I expect you can find models of such letters by searching for them on the internet, and there are also some on these ESOLNexus and BBC pages. 'permission' is often followed by a to + infinitive, so I'd say something like '... your permission not to attend the meeting today', but check for examples on those pages for other ideas, too.

All the best,
The LearnEnglish Team

What is the difference between could and may? I they both express the same thing, that is, could is used for hypothetical situation in the future.

John is coming to visit. He could stay with us.
John is coming to visit. He may stay with us.

Hello akatsuki,

Modal verbs can have a range of meanings in different contexts. Here, 'could' tells us that something is possible. 'May' can mean the same, or it can mean that the speaker agrees to let John stay.

Best wishes,


The LearnEnglish Team

hello sir could you pls tell me, what is the difference b/w "can be find and can be found" with examples