1.Complete the sentences with must or mustn't and the verb in brackets.
1 Children .... (go) to school.
2 You... (wear) a helmet when you ride a motorbike.
3 You... (swim) on a beach when the flag is red. 4 You .... (talk) in a library.
5 When the traffic lights are red, you .... (stop).
6 You .... (forget) your passport when you travel to another country.

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