Examples with must in negative

Must not, Mustn't (prohibition) We use must not to say that something is not permitted or allowed, for example: Passengers must not talk to the driver. Structure of Must not Must is an auxiliary verb. It is followed by a main verb. The structure for must not is: subject + must not + main verb The main verb is the base verb (infinitive without "to"). Must not is often contracted to mustn't. Look at these examples: subject auxiliary must + not main verb I mustn't forget my keys. You mustn't disturb him. Students must not be late. NB: like all auxiliary verbs, must CANNOT be followed by "to". So, we say: You mustn't arrive late. (not You mustn't to arrive late.) Use of Must not Must not expresses prohibition - something that is not permitted, not allowed. The prohibition can be subjective (the speaker's opinion) or objective (a real law or rule). Look at these examples: I mustn't eat so much sugar. (subjective) You mustn't watch so much television. (subjective) Students must not leave bicycles here. (objective) Policemen must not drink on duty. (objective) We can use must not to talk about the present or the future: Visitors must not smoke. (present) I mustn't forget Tara's birthday. (future) We cannot use must not to talk about the past. We use other structures to talk about the past, for example: We were not allowed to enter. I couldn't park outside the shop.