Usage of MUST

Usage of MUST

(Necessity, Obligation and Certainty) 

1. Used to say that something is necessary or very important (sometimes involving a rule or a law).

o  All visitors must report to reception.

o  Cars must not park in front of the entrance (= it is not allowed).

o  I must ask you not to do that again.

o  You mustn’t say things like that.

o  I must go to the bank and get some money.

o  I must admit (= I feel that I should admit) I was surprised it cost so little.

o  Must you always question everything I say? (= it is annoying)

o  ‘Do we have to finish this today?’ ‘Yes, you must.’

2. Used to say that something is likely or logical.

o  You must be hungry after all that walking.

o  He must have known (= surely he knew) what she wanted.

o  I’m sorry, she’s not here. She must have left already (= that must be the explanation).

3. Used to recommend that sb does something because you think it is a good idea.

o  You simply must read this book.

o  We must get together soon for lunch.

4. If you 'must (do something): used to say that sb may do something but you do not really want them to.

o  ‘Can I smoke?’ ‘If you must.’

o  It’s from my boyfriend, if you must know.

5. must-see / must-read / must-have, etc.: used to tell people that something is so good or interesting that they should see, read, get it, etc.

o  Sydney is one of the world’s must-see cities.

o  The magazine is a must-read in the show business world.

6. Must and have to are used in the present to say that something is necessary or should be done. Have to is more common in American English, especially in speech.

o  You must be home by 11 o’clock.

o  I must wash the car tomorrow.

o  I have to collect the children from school at 3 o’clock.

o  Nurses have to wear a uniform.

7. In British English there is a difference between them. Must is used to talk about what the speaker or listener wants, and have to about rules, laws and other people’s wishes.

o  I must finish this essay today.

o  I'm going out tomorrow.

o  I have to finish this essay today.

o  We have to hand them in tomorrow.

8. There are no past or future forms of must. To talk about the past you use had to.

o  I had to wait half an hour for a bus.

9. Will have to is used to talk about the future (or) Have to is used if an arrangement have already   been made.

o  We’ll have to borrow the money we need.

o  I have to go to the dentist tomorrow.

10. Questions with have to are formed using do.

o  Do the children have to wear a uniform?

11. In negative sentences both must not and don’t have to are used, but with different meanings. Must not is used to tell somebody not to do something.

o  Passengers must not smoke until the signs have been switched off.

o  You mustn’t leave the gate open.

12. Don’t have to is used when it is not necessary to do something.

o  You don’t have to pay for the tickets in advance.

o  She doesn’t have to work at weekends.

13. Both must and have to are used to say that you are certain about something. Have to is the usual verb used in American English and this is becoming more frequent in British English in this meaning.

o  He has to be the worst actor on TV!

o  This must be the most boring party I’ve ever been to.

14. If you are talking about the past, use must have.

o  Your trip must have been fun!

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