1. You aren’t allowed to make noise in the library. – You mustn’t....make noise in the library..

2. It isn’t necessary for you to go to school so early. -> You don’t .go to school so early.

3. It is a good thing for you to keep the house clean and tidy. ->You ought.. to keep the house clean and tidy.

4. I had a good time at the party last night. -> I enjoyed.. go at the party last night.

5. Must he leave now? -> Does he ..........leave now..........................?

6. Playing with matches is very dangerous. -> It is very dangerous to play with matches

7. You must stay in bed because of your illness. -> You must stay in bed because..you are ill 

8. It isn’t necessary for you to water that tree every day.-> You don’t.....water that tree every day

9. It is dangerous to put a knife into an electrical socket. -> Putting a knife.is put a knife into an electrical socket