English Grammar in Use With Answers » Unit 31: Have to and must

I have to do something = it is necessary to do it, I am obliged to do it:
  • You can't turn right here. You have to turn left.
  • I have to wear glasses for reading.
  • Robert can't come out with us this evening. He has to work late.
  • Last week Tina broke her arm and had to go to hospital.
  • I haven't had to go to the doctor for ages.

We use do/does/did in questions and negative sentences (for the present and past simple):
  • What do I have to do to get a new driving licence? (not What have I to do?)
  • Karen doesn't have to work Saturdays. (not Karen hasn't to)
  • Why did you have to leave early?

You can say I'll have to ... , I'm going to have to ... and I might / I may have to ... :
  • They can't fix my computer, so I'll have to buy a new one. or I'm going to have to buy a new one.
  • Tom might have to work late tomorrow. or Tom may have to work ... (= it's possible that he will have to)

Must is similar to have to:
  • It's later than I thought. I must go. or I have to go.

You can use must or have to to give your own opinion (for example, to say what you think is necessary, or to recommend someone to do something):
  • I haven't spoken to Sue for ages. I must phone her. / I have to phone her. (= I say this is necessary)
  • Mark is a really nice person. You must meet him. / You have to meet him. (I recommend this)

We use have to (not usually must) to say what someone is obliged to do. The speaker is not giving his/her own opinion:
  • I have to work from 8.30 to 5.30 every day. (a fact, not an opinion)
  • Jane has to travel a lot for her work.

But must is used in written rules and instructions:
  • Applications for the job must be received by 18 May.
  • (exam instruction) Answer all the questions. You must write your answers in ink.

You cannot use must to talk about the past :
  • We didn't have much time. We had to hurry. (not we must hurry)

Mustn't and don't have to are completely different:

You mustn't do something = it is necessary that you do not do it (so don't do it):You don't have to do something = you don't need to do it (but you can if you want):
You must keep this a secret . You mustn't tell anyone. (= don't tell anyone)You don't have to tell Tom what happened. I can tell him myself.
I promised I would be on time. I mustn't be late. (= I must be on time)I don't have to be at the meeting, but I think I'll go anyway.

You can use have got to instead of have to. So you can say:
  • I've got to work tomorrow. or I have to work tomorrow.
  • When has Helen got to go? or When does Helen have to go?

31.1 Complete the sentences using have to / has to / had to.

  1. Bill starts work at 5 a.m. at four. (he / get up)
  2. ‘I broke my arm last week.’ ‘ to hospital?’ (you / go)
  3. There was a lot of noise from the street. __________ the window. (we / close)
  4. Karen can't stay for the whole meeting. __________ early. (she / leave)
  5. How old __________ to drive in your country? (you / be)
  6. I don't have much time. __________ soon. (I / go)
  7. How is Paul enjoying his new job? __________ a lot? (he / travel)
  8. ‘I'm afraid I can't stay long.’ 'What time __________ ?’ (you / go)
  9. ‘The bus was late again.’ 'How long __________ ?’ (you / wait)
  10. There was nobody to help me. I __________ everything by myself. (I / do)

31.2 Complete the sentences using have to + the verbs in the list. Some sentences are positive (I have to ... etc.) and some are negative (I don't have to ... etc.):

  • ask
  • do
  • drive
  • get up
  • go
  • make
  • make
  • pay
  • show
  1. I'm not working tomorrow, so I early.
  2. Steve didn't know how to turn off the computer, so I him.
  3. Excuse me a moment - I __________ a phone call. I won't be long.
  4. I'm not too busy. I have a few things to do, but I __________ them now.
  5. I couldn't find the street I wanted. I __________ somebody for directions.
  6. The car park is free. You __________ to park your car there.
  7. A man was injured in the accident, but he __________ to hospital because it wasn't serious.
  8. Jane has a senior position in the company. She __________ important decisions.
  9. When Patrick starts his new job next month, he __________ 50 miles to work every day.

31.3 In some of these sentences, must is wrong or unnatural. Correct the sentences where necessary .

  1. _____ It's later than I thought. I must go.
    __________
  2. _____ I must work every day from 8.30 to 5.30.
    __________
  3. _____ You must come and see us again soon.
    __________
  4. _____ Tom can't meet us tomorrow. He must work.
    __________
  5. _____ I must work late yesterday evening.
    __________
  6. _____ I must get up early tomorrow. I have a lot to do.
    __________
  7. _____ Julia wears glasses. She must wear glasses since she was very young.
    __________

31.4 Complete the sentences with mustn't or don't/doesn't have to.

  1. I don't want anyone to know about our plan. You tell anyone.
  2. Richard wear a suit to work, but he usually does.
  3. I can sleep late tomorrow morning because I __________ go to work.
  4. Whatever you do, you __________ touch that switch. It's very dangerous.
  5. There's a lift in the building, so we __________ climb the stairs.
  6. You __________ forget what I told you. It's very important.
  7. Silvia __________ get up early, but she usually does.
  8. Don't make so much noise. We __________ wake the children.
  9. I __________ eat too much. I'm supposed to be on a diet.
  10. You __________ be a good player to enjoy a game of tennis.

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