MEKNES ENGLISH CORNER

Auxiliary

Uses

Present / future

Past

may

1. polite request

May I borrow your pen?

2. formal permission

You may leave the room.

3. possibility

--Where's Jon?

He may be at the library

He may have been at the library

might

1. possibility

--where's John?

He might be at the library

He Might have been at the library

2. polite request (rare)

Might I borrow your pen?

should

1. advisability

I should study tonight

I should have studied last night.

2. 90% certainty

She should do well on the test (future only, not present)

She should have done well on the test.

ought to

1. advisability

I ought to study tonight

I ought to have studied last night

2. 90% certainty

She ought to do well on the test. (future only, not present)

She ought to have studied last night.

had better

1. advisability with threat of bad result

You had better be on time, or we will leave without you.

(past form uncommon)

must

1. strong  necessity

I must go to class today

I had to go to class yesterday

2. prohibition (negative)

You must not open that door.

3. certainty

Mary isn't in class. She must be sick (present only)

Mary must have been sick yesterday.

have to

1. necessity

I have to go to class today.

I had to go to class yesterday

2. lack of necessity (negative)

I don't have to go to class today.

I had to go to class yesterday.

have got to

1. necessity

I have got to go to class today.

I had to go to class yesterday.

will

1. 100% certainty

He will be here at 6:00 ((future only)

2. willingness

--the phone's ringing.

I'll get it.

3. polite request

Will you please pass the salt?

can

1. ability / possibility

I can run fast.

I could run fast when I was a child but now I can't.

2. informal permission

You can use my car tomorrow.

3. informal polite request

Can I borrow your pen?

4. impossibility (negative only)

That can't be true!

That can't have been true!

could

1. past ability

I could run fast when I was a child.

2. polite request

Could I borrow your pen?

Could you help me/

3. possibility

--Where's John?

He could be at home.

He could have been at home.

4. impossibility (negative only).

That couldn't be true!

That couldn't have been true!

be able to

1. ability

I am able to help you. I will be able to help you.

I was able to help him.

shall

1. polite question to make a suggestions

Shall I open the window?

2. future with "I" or "we" as subject

I shall arrive at nine. (will = more common)