We use “must” and “have to” to say that it is necessary to do something. Sometimes it doesn’t matter which you use:
- Oh, it’s later than I thought. I must go OR I have to go.
But there is a difference between “must” and “have to” and sometimes this is important: must is personal. We use “must” when we give our personal feelings.
- You must do something = “I” (the speaker) say it is necessary.
- She’s a really nice person. You must meet her. (I say it is necessary.)
- I haven’t phoned Lily for ages. I must phone her tonight.
“Have to” is impersonal. We use it when we are talking about facts, not our personal feelings. You “have to” do something because of a rule or the situation:
- You can’t turn right here. You have to turn left. (It’s against the law to turn right.)
- My eyesight isn’t very good. I have to wear glasses for reading. (I can’t read without them.)
- Lily can’t come out with us this evening. She has to work. (She has an obligation.)
- I have to get up early tomorrow. I’m going away and my train leaves at 7:30. (Because of the train schedule, it is necessary for me to get up early.)
NOTE: If you are not sure which to use, it is usually safer to use “have to”.
You can use “must” to talk about the present or future BUT not the past.
- We must go now.
- We must go tomorrow.
- WRONG: We must go yesterday.
You can use have to in all forms.
- I had to go to the hospital. (past)
- Have you ever had to go to the hospital? (present perfect)
- I might have to go to the hospital. (infinitive after might)
In questions and negative sentences with “have to”, we use the auxuliary verb DO (do/does/did):
- What do I have to do to get a driving license? (not ‘what have I to do?)
- Why did you have to go to the hospital?
- Salma doesn’t have to go to work on Saturdays.
“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 must keep a secret. You mustn’t tell anyone. (so don’t tell anyone!)
- I promised I would be on time. I mustn’t be late. (so I must be on time!)
You don’t have to do something = you don’t need to do it (but you can if you want).
- You can tell me if you want but you don’t have to tell me = you don’t need to tell me.
- I’m not working tomorrow, so I don’t have to get up early.
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 Nina got to go?” or “When does Nina have to go?”
HAVE TO & MUST Quiz 2
Complete the following sentences by inserting either "must" or "have to" where it's necessary!
You can try our other quizes here.
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