GUIDE ENGLISH GRAMMAR BOOK

PAGE 123
97 Possibility
2 Can and could
a
b
c
d
e
We use can and could to suggest possible future actions.
You can/could go on the train, of course.
We can/could have a party. ~ Yes, why not?
If we're short of money, I can/could sell my jewellery.
Can is stronger than could, which expresses a more distant possibility.
We use can and could in requests. Could is more tentative.
Can/Could you wait a moment, please?
Can/Could I have one of those leaflets, please?
We also use can for an offer.
I can lend you a hand. Can I give you a lift?
Can and could express only a possibility. They do not mean that something is likely
to happen.
We can/could have a party. ~ Yes, why not? (suggestion)
We may/might have a party. ~ Oh, really? (uncertain intention)
For something that is possibly true, we use could.
Tina could be working late tonight.
The timetable could be in this drawer.
You could have forgotten to post the letter.
We can also use may or might here, but not can.
For an uncertain prediction about the future, we also use could, may or might but
not can.
The motorway could be busy tomorrow.
There is a special use of can to say that something is generally possible.
You can make wine from bananas. Smoking can damage your health.
Can often has the meaning 'sometimes'.
Housewives can feel lonely. (= They sometimes feel lonely.)
The motorway can get busy. (= It sometimes gets busy.)
NOTE
Tend to has a similar meaning.
Americans tend to eat a lot of meat.
Dog owners tend to look like their dogs.
f
Can't and couldn't express impossibility.
She can't be very nice if no one likes her.
You can't/couldn't have seen Bob this morning. He's in Uganda.
Compare can't with may not/might not.
This answer can't be right. It must be wrong.
(= It is impossible for this answer to be right.)
This answer may not/might not be right. It may/might be wrong.
(= It is possible that this answer isn't right.)