Modal verbs

might

I might = it is possible that I will:

I might go to the cinema this evening, but I’m not sure. (= it is possible that I will go)
A: When is Rebecca going to phone you?
B: I don’t k now. She might phone this afternoon.
Take an umbrella with you. It might rain.
Buy a lottery ticket. You might be lucky. (= perhaps you will be lucky)
‘Are you going out tonight?’ ‘I might.’ (= I might go out)

Compare
I‘m playing tennis tomorrow. (sure)
I might play tennis tomorrow. (possible)
Rebecca is going to phone later. (sure)
Rebecca might phone later. (possible)

I might not = it is possible that I will not:
I might not go to work tomorrow. (= it is possible that I will not go)
Sue might not come to the party. (= it is possible that she will not come)

may

You can use may in the same way. I may = I might:
I may go to the cinema this evening. (= I might go)
Sue may not come to the party. (= Sue might not come)

May I … ? = Is it OK to … ? / Can I … ?:

May I ask a question? (= is it OK to ask / can I ask?)
‘May I sit here?’ ‘Yes, of course.’

can and could

I can do something = I know how to do it, or it is possible for me to do it:
–
D I can play the piano. My brother can play the piano too.
D Sarah can speak Italian, but she can’t speak Spanish.
D ‘Can you swim?’ ‘Yes, but I’m not a very good swimmer.’
D ‘Can you change twenty pounds?’ Tm sorry, I can’t.’
D I’m having a party next week, but Paul and Rachel can’t come.

For the past (yesterday/ last week etc.), we use could/couldn’t:
D When I was young, I could run very fast.
do?
play?
see?
come? etc.
D Before Maria came to Britain, she couldn’t understand much English. Now she can
understand everything.
D I was tired last night, but I couldn’t sleep. D l had a party last week, but Paul and Rachel couldn’t come.

Can you … ? Could you … ? Can I … ? Could I … ?

We use Can you … ? or Could you … ? when we ask people to do things:

Can you open the door, please? or Could you open the door, please?
Can you wait a moment, please? or Could you wait … ?

We use Can I have … ? or Could I have … ? to ask for something:

(in a shop) Can I have these postcards, please? or Could I have … ?

Can I … ? or Could I … ? = is it OK to do something?:

Tom, can I borrow your umbrella? or Tom, could I borrow your umbrella?
(on the phone) Hello, can I speak to Gary, please? or … could I speak … ?

must / mustn’t / don’t need to

I must (do something)

= I need to do it:
I’m very hungry. I must eat something.
It’s a fantastic film. You must see it.
The windows are very dirty. We must clean them.

For the past (yesterday / last week etc.), we use had to … (not must):

I was very hungry. I had to eat something. (not I must eat)
We had to walk home last night. There were no buses. (not We must walk)

mustn’t

I mustn’t (do something) = it is necessary not to do it, it is the wrong thing to do: 一定不要

I must hurry. I mustn’t be late.
I mustn’t forget to phone Jane. (= I must remember to phone her)
Be happy! You mustn’t be sad. (= don’t be sad)
You mustn’t touch the pictures. (= don’t touch the pictures)

don’t need to

I don’t need (to do something) = it is not necessary:

I don’t need to go yet. I can stay a little longer.
You don’t need to shout. I can hear you OK.

You can also say don’t have to …

D I don’t have to go yet. I can stay a little longer.

Compare

don’t need to and mustn’t:

You don’t need to go. You can stay here if you want.
You mustn’t go. You must stay here.

should

You should do something = it is a good thing to do, it is the right thing to do:

Tom doesn’t study enough. He should study harder.
It’s a good film. You should go and see it.
When you play tennis, you should always watch the ball.

You shouldn’t do something = it is not a good thing to do.

Tom shouldn’t go to bed so late.
You watch TV aU the time. You shouldn’t watch TV so much.

We often say I think . . . should …

I think … should …

I think Lisa should buy some new clothes. (= I think it is a good idea.)
It’s late. I think I should go home now.
A: Shall I buy this coat?
B: Yes, I think you should.

I don’t think … should …

I don’t think you should work so hard. (= I don’t think it is a good idea.)
I don’t think we should go yet. It’s too early.

Do you think . . . should … ?

Do you think I should buy this hat?
What time do you think we should go home?

Compare

Must is stronger than should:

It’s a good film. You should go and see it.
It’s a fantastic film. You must go and see it.

Another way to say should is ought to:

It’s a good film. You ought to go and see it. (= you should go)
I think Lisa ought to buy some new clothes. (= Lisa should buy)

I have to …

I have to do something = it is necessary for me to do it, I am obliged to do it

I’ll be late for work tomorrow. I have to go to the dentist.
Jane starts work ac 7 o’clock, so she has to get up at 6.
You have to pass a test before you can get a driving licence.

What time do you have to go to the dentist tomorrow?
Does Jane have to work on Sundays?
Why did they have to leave the party early?

I don’t have to (do something) = it is not necessary to do it:

I’m not working tomorrow, so I don’t have to get up early.
Ian doesn’t have to work very hard. He’s got an easy job.
We didn’t have to wait very long for the bus – it came in a few minutes.

Compare

must and have to

You can use must or have to when you say what you think is necessary, when you give your opinion:

It’s a fantastic film. You must see it. or You have to see it.

When you are not giving your personal opinion, use have to (not must). Compare:

Jane won’t be at work this afternoon. She has to go to the doctor.
(this is not my personal opinion – it is a fact)
Jane isn’t well. She doesn’t want to go to the doctor, but I told her she must go.
(this is my personal opinion)