Unit 31. Have to and must.
Unit 31; Part A
![]() • You can't turn right here. You have to turn left. • I have to wear glasses for reading. • George 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 use have to with will and might/may: • If the pain gets worse, you'll have to go to the doctor. • I might have to work late tomorrow evening. or I may have to work ... (= it's possible that I will have to) |
Unit 31; Part B

• It's later than I thought. I must go. or I have to go.
You can use must to give your own opinion (for example, to say what you think is necessary, or to recommend someone to do something). Have to is also possible:
• I haven't spoken to Sue for ages. I must phone her. (= I say this is necessary)
• Mark is a really nice person. You must meet him. (I recommend this)
We use have to (not 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 often used in written rules and instructions:
• Applications for the job must be received by 18 May.
• (exam instruction) You must write your answers in ink.
You cannot use must to talk about the past:
• We had to leave early. (not we must)
Unit 31; Part C

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 it a secret. You mustn't tell anyone. (= don't tell anyone) | • You don't have to tell him, but you can if you want to. |
• 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. |
Unit 31; Part D

• I've got to work tomorrow. or I have to work tomorrow.
• When has Liz got to go? or When does Liz have to go?
Exercises
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