MUST

(NECESSARY) [auxiliary verb] [+ infinitive without to] he/she/it must - used to show that it is necessary or very important that something happens in the present or futureYou must take these pills every day.This letter must not be shown to anyone else.Luggage must not be left unattended (= it is against the rules)."Must you leave so soon?" "Yes, I must.""Can you let me come in?" "No, I mustn't.""Must I sign this?" "No, you needn't."USAGE: When talking about things that were necessary in the past, it is usual to use had to: I must go tomorrow. I had to go yesterday. When describing what someone said in the past, must or had to can be used as the past form: He told me that I must sit down means He said "You must sit down".If you say that you must do something, you might mean that you have a firm intention to do something in the future.I must phone my sister.I mustn't bite my nails.We mustn't argue any more.Must is sometimes used for emphasis.I must admit I didn't know what to do.You're looking very well, I must say.If you tell someone else that they must do something pleasant, you are emphasizing that you think it is a good idea for them to do that.You must come and stay with us for the weekend.We must meet for lunch soon.