Use of Can, could, May & Might

A.

Can usually express ability or capacity as in:

Can you read French?

Can I use your telephone?

Can you lift this table?

Can you help me in this matter?

I can study till late at night.

I can feel the heat of summer.

I can swim across the lake.

He can work on this problem.

B.

Can and May are used to ask for permission and give permission and give permission. May is usually considered more formal and polite than can; as

You can/may watch TV after dinner.

You can go now.

You may go now.

Can I borrow your work book?

May I borrow your umbrella?

C.

Can and May are also used to express the possibility of an action or event. May is usually used to refer to a less likely possibility than can as in:

We can have the meeting at 3 p.m. (definite possibility)

We may have meeting at 3 p.m. (slight possibility)

It may rain tomorrow.

He may be at home.

Can this be true?

It cannot be true.

Compare ‘It cannot be true’ with ‘It may not be true’. Cannot denotes impossibility, while may not denotes improbability.

D.

In very formal English, may is used to express a wish as in:

May God bless you!

May you succeed!

May you live happily and long!

May you have success in all your attempts!

E.

Could and might are used as the past equivalents of can and may:

I could swim across the lake when I was young. (Ability)

He said I might / could go. (Permission)

I thought he might be at home.

F.

In present – time contexts could and might are used as less positive versions of can and may;

I could attend the seminar.

(Less positive and more hesitant than ‘I can attend the seminar’.)

Might/ Could I borrow your umbrella?

(A diffident way of saying ‘May/ can I…..’)

It might rain tonight.

(Less positive than ‘It may rain…..’)

Could you pass me the water jug?

(Polite request)

G.

Do not confuse may be with maybe. May be is a verb Maybe is an adverb meaning ‘perhaps’. It can also be the answer we give when we don’t want to say either ‘yes’ or no’;

She may be late

She maybe late

Maybe she will be late.

H.

Could can be used in many different ways, to ask for permission, to make a request or to express ability when referring to the past. Was able to is sometimes used as an alternative to could when we are discussing ability or possibility. We tend to use could when we are talking about ability generally. Compare the following:

By the time she was seven, she could already speak three languages.

She started the viola at the age of eight and after only six months she could play it quite well.

Her brother Jack was an excellent swimmer. He could beat anybody in his class.