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.
Ability
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]
Permission
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.
Requests
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?
Offers
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.
Suggestions
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 ...? etc. |
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
Hello Crokong,
As you know, most modal verbs have a number of different uses and can and could are no exceptions. Both can be used to make suggestions:
Could is a little more tentative in these kinds of sentences, I would say, which is probably what your grammar book had in mind.
Peter
The LearnEnglish Team
Hello Crokong,
Yes, that's right. The speaker is a little less certain of his or her choice, claim, suggestion or opinion.
Peter
The LearnEnglish Team
Hi amit_ck,
Yes, the sentence is correct! Here is the basic structure, with some examples.
A and B are noun phrases (underlined). Can is part of an added clause, not part of the A noun phrase. That's why it's not added to B at the end of the sentence.
You could add 'can' at the end for extra emphasis. In this case, I'd probably say it like this, to separate the two clauses:
I hope that helps :)
Jonathan
The LearnEnglish Team
Hello DaniWeebKage,
Your first sentence is not correct as it appears to describe a current situation (being lost); this would mean that you are speculating rather than describing what is generally possible. Note that in the example on the page the verb is 'get lost', which does not describe a current state. Your second sentence is fine. It expresses speculation about the present and has a similar meaning to 'maybe' or 'perhaps'.
You can get lost easily in this town. [a general statement about the town: it is possible because the town's layout is confusing]
You could get lost easily in this town. [a specific statement about your trip: there is a chance of this happening]
Peter
The LearnEnglish Team
Hello again DaniWeebKage,
We wouldn't use this formulation. To speculate about what may or may not be true at the moment we use could (You could be lost).
Can describes something which is not impossible. Of course a person can be lost, but it is a banal statement without any real meaning.
Think about it this way: when we are talking about how a person feels we say 'He could be angry', meaning 'there is a chance he is angry'. We don't say 'He can be angry' because it is obvious: anyone can be angry at any time.
Peter
The LearnEnglish Team
Hello nsnaveensorout,
Yes, that's one use of 'could'. It can describe present or future possibility, as the first two examples on the page show:
Peter
The LearnEnglish Team
Hello Dwishiren,
When we make suggestions both are often possible and have verb similar meanings. We can use can with a general (this is possible) or specific meaning, while could tends to be specific to a situation (in this situation it is possible).
Peter
The LearnEnglish Team
Hello sir,
I still have a doubt about the difference between the followings
You might use 'can' to make requests in a friendly way.
You could use 'can' to make requests in a friendly way.
Both could and might are used to make suggestions. So, pls tell me the subtle difference between them so that i will be able to satisfy my students with that subtle distinction.
Thank u, sir.
Hello Kumaraswamy,
You're right that any distinction here is very subtle and would likely be overwhelmed by aspects such as tone and expression. That said, to my ear could sounds more neutral ("here is a possibility") while might implies more of a personal opinion ("I think this is the best choice").
You can read a discussion on the topic here:
https://ell.stackexchange.com/questions/20003/might-and-could-used-for-making-suggestions
Peter
The LearnEnglis
Hi Crokong,
You have two different uses here.
In the first example, could expresses possibility and has a similar meaning to might: this is something that has a chance of happening.
In the second example the meaning is also about possibility but in the sense of making an offer or a proposal. Here, it has a similar meaning to able to: we are able to give him a place to stay.
Peter
The LearnEnglish Team
Hi mary_1565,
Yes, it's grammatically correct :)
Jonathan
The LearnEnglish Team
Hello BobMux,
I'd say that is a general statement about what is possible.
All the best,
Kirk
The LearnEnglish Team
Hi Rsb,
Yes, I think it's a suggestion too! It could be a request if it was in the question form: Could you help?
Best wishes,
Jonathan
The LearnEnglish Team
Hello Gloria,
I'm not in a position to say that other text books are wrong, but I can tell you what I understand to be correct.
I would not use pattern 1 with 'recommend', but in at least one of my reference books, it is listed as correct, so I would go with that. Neither I nor my reference book consider pattern 1 correct with 'suggest'. In general, I would avoid the passive here, even though it might be grammatically correct in some cases.
I'm not sure if pattern 2 is incorrect or not, but I'd recommend avoiding it. If it's really necessary to specify that the advice for another person was given to a different person, I'd use a couple of sentences to explain that.
As for pattern 3, as far as I understand it, only 'do' is really correct here. This is an example of the subjunctive, which is far less developed in English than in Spanish; in this case, 'do' is a translation of both 'haga' and 'hiciera/hiciese' and so you'd need some other phrase (or the context) to make it clear if the recommendation is speaking about the present/future or the past.
I should mention that most native speakers of English don't know what the subjunctive is, and so you might find them using 'does' or 'did' where I've said you should use 'do'. I believe most editors, though, would recommend 'do' here.
Hope that helps. Happy New Year to you too!
All the best,
Kirk
The LearnEnglish Team
Hi Stellaaa,
You can use 'can' to speak about someone's ability to do something in general ('She can swim'), and you can also use it to speak about how they manage to do something in a specific situation ('I can help you now').
You can use 'could' to speak about someone's ability in the past ('My grandmother could speak Swedish') but not to speak about how they managed to do something in a specific situation (not 'The fire brigade
could rescuethe child', instead: 'The fire brigade was able to rescue the child').All the best,
Kirk
The LearnEnglish Team
Hello Yigido,
All of the modal verbs have several different meanings and uses. In this case, it sounds to me as if 'couldn't' is speaking about a hypothetical situation: if he wanted to be a basketball player, he could not be one because he isn't tall enough.
Does that make sense?
All the best,
Kirk
The LearnEnglish Team
Hello Yigido,
I think I'd recommend you ask your teacher about this one, as he or she will know what exactly the mean to say. In general, though, 'could' refers to ability in the past, or, as I mentioned, it can refer to a hypothetical situation (with the meaning of 'would be able to').
Hope this helps.
All the best,
Kirk
The LearnEnglish Team
Hello Mison,
It's fine to use 'could' in that way. Well done!
Peter
The LearnEnglish Team
Hello aliakar86,
I'm afraid that it's not correct to use 'mustn't have' in the ways you ask about because in English you can't prohibit something that already happened. For example, it's not correct to say to your friend 'You must not have gone outside' -- instead, you should say 'You shouldn't have gone outside'.
Similarly, to your friend who got poor exam results, you should say 'You should have studied more' instead of 'You must have studied more'.
It is correct to use 'must have' for deductions. You can see more about this on our Modals – deductions about the past page. I think that should be quite clear, but if you have any more questions, please let us know.
All the best,
Kirk
The LearnEnglish Team
Hello IsabelTim_123,
'may be', 'might be' and 'could be' would all mean the same thing in this sentence: these animals are possibly dangerous, but I'm not sure. You might say this, for example, when you see some animals you're unfamiliar with (e.g. wild pigs) and you really don't know anything about them. But since they are wild animals, there is the possibility that they are dangerous.
'can be' is used to speak more about a possibility we are familiar with -- it suggests that you know something about the animals. If, for example, you see those wild pigs and know for a fact that in some situations they are dangerous --perhaps your grandfather told you this -- and using 'can' would express this idea. Perhaps they won't be dangerous in this situation, but you know that in some cases they are.
Hope this helps you make sense of it.
All the best,
Kirk
The LearnEnglish Team
Hi smit,
Yes, that's right! To work out which meaning is intended by a speaker or writer, we need to consider the context. That includes other things the speaker or writer says, and details about the situation (e.g. the place, the time, the relationship between the speakers, other topics in the conversation).
The examples above are isolated sentences, so they don't have much contextual information. For example, one sentence above is:
But, in real speaking or writing, it would have more context, for example:
The context gives us clues (e.g. when she was little) to show that could means 'past ability' here, and not 'possibility'.
Does that make sense?
Best wishes,
Jonathan
The LearnEnglish Team
Hi smit,
In this example, could doesn't work. Could is for a past ability (not present ability). Could can mean possibility in the present, but speaking English is an ability, not a possibility.
If I'm not 100% sure, I would say: She might be able to. (Might shows a lack of certainty.)
Best wishes,
Jonathan
The LearnEnglish Team
Hello IsabelTim_123,
In 1 and 2, 'could' is also possible and I'd understand it to mean the same thing. In 3, there is nothing grammatically wrong with saying 'can', but it's not really an appropriate response to the question. The question asks for ideas and usually we use a hypothetical form like 'could' to answer such a question, not a form that speaks about ability. In 4, 'cannot have' is not correct because the sentence is speaking about an unreal past, i.e. a past condition that didn't really exist. 'cannot have' makes a statement about a real past action which we think did not occur.
All the best,
Kirk
The LearnEnglish Team
Hello Anisha00329,
Yes, you could use 'can' is all three of those sentences to mean the same thing.
As for the sentences about a rash, both 'can' or 'may' are also possible here if you're speaking about a general possibility, but 'could' is also fine if, for example, you're a concerned parent looking at the rash and deciding whether to take that person to the hospital.
All the best,
Kirk
The LearnEnglish Team