practical grammar I MODALS

Must

The verb must has four principal meanings, each one of which has a different negative form.

Positive negative

I. obligation I. a. prohibition

You must go to school between

You have been very ill and you must not go back to school for at the ages of five and fifteen. least a month.

b. lack of obligation: it is voluntary

You don't have to go to school after the age of fifteen unless you want to.

II. necessity II. lack of necessity

You must work hard if you are going to You needn't work hard to pass that pass that examination. Examination.

III. supposition or deduction III. negative supposition

It must be his sister. It can't be his sister.

IV. desirability IV. undesirability

You must see that film: it's wonderful. You had better not see that film. It would only upset you.

The past tense of must in the meaning of obligation needs some attention.

present past

You must play football at that school. You had to play football when you were at that school.

direct speech

You must not play football this year. 'I was not allowed to play football that year.'

indirect speech

The doctor said he was not to play football that year.

(It is normal to omit allowed or permitted in indirect speech.)

There is a distinction between must and have to.

Must is more of an emphatic exhortation and more of an assertion of personal authority than have to, which is used for a necessity fixed by laws and rules and implies a detached attitude.

Must, however, is the one used on public notices.

You must come with me this minute.

You must do as you are told. (Assertions of personal authority.)

You must think again: I cannot see you throw away your life like this. (An exhortation.)

Passengers must cross the line by the footbridge.

Passports must be shown at the frontier. (Public notices.)

You have to get a driving licence before you are allowed to drive. (An impersonal statement: that is the law.)

You have to abide by the referee's decision, whatever sport you are playing. (It is a general rule.)

Students have to find their own way to the examination centre. (That is the normal procedure. The speaker takes up a detached attitude.)

You may have to pay alimony if the divorce goes through. (That is the normal procedure. I cannot make any exceptions in your case.)

Questions containing must may have to be answered with need and vice versa.

'Must you take the examination?' 'No, I needn't if I don't want to.'

'Need you leave so early?' 'Yes, I'm afraid I must.'

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