Modal verbs: can, may, must 18.05-24.05

Can, could, and be able to

  • We use can to say that something is possible or that somebody has the ability to do something.

e.g. He can speak many foreign languages.

  • The negative is can’t.
  • But can has only two forms can(present) and could (past).
  • Can has no future and present perfect that is why in those cases we use be able to.

e.g. I will be able to meet you tomorrow.

They haven’t been able to sleep recently.

May and Might

  • We use may or might to say that something is a possibility.

It may be true.(present)

It might be true.(past)

It might rain.(future- perhaps it will rain)

  • The negative forms are may not and might not (mightn’t)


I,you,he….etc   may(might)  not  be (true, at home, in the office)

                                                   not be (doing, working,having)

                                                   not    do, know, have , want

Must and have to

  • We use must and have to to say that it is necessary to do something.

E/g I must go or I have to go

  • The negative forms are mustn’t and don’t have to(doesn’t have to)
  • The difference between must and have to:

You must do something.

You must meet her.

In both cases the speaker says that it is necessary.

You can’t turn right here, you have to turn left.(because of the traffic system)

I have to get up early tomorrow.My train leaves at 7:30


  1. Complete the sentences using can, could, be able to

1.John has traveled a lot. He can speak four languages.

2.I haven’t can sleep very well lately.

3. She could drive, but she hasn’t got a car.

4. I can see you on Friday, but I be able to meet you on Saturday.

5. You look tired. – Yes, I can’t sleep last night.

6.I was feeling sick yesterday. I couldn’t eat anything.

7.They didn’t want to come with us, but we could  persuade them.

2. Use may or might

1.I was surprised, that Sarah wasn’t at the meeting.- She might not have known  about it.

2. He may be in the office.

3. Ask Ann, she may know.

4.I haven’t decided where I am going for holidays. I might go to England.

5.Take the umbrella. It might rain later.

3.Use must, mustn’t , have to , don’t/doesn’t have to

  1. I promised I would be on time. I mustn’t be late.
  2. I’m not working tomorrow, so I mustn’t to get up early.
  3. What do I have to do to get a driving license?
  4. I haven’t phoned Ann for ages, I have to phone her tonight.
  5. I don’t want anyone to know. You mustn’t tell anyone.
  6. He must wear a suit to work, but he usually does.
  7. We haven’t got much time. We must hurry.

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