Fill in the gaps with mustn’t or needn’t.

A teacher is speaking to his students before a test:
«You are going to have a test today. Your test papers are on your desks. You 1) mustn’t begin until I tell you. You 2) …… hurry; you have plenty of time. You 3) …… speak during the test. You 4) …… write in pen; if you prefer you can write in pencil. You 7) …… stay when you’ve finished; you can leave if you want to, but you 8) …… be noisy. When you leave you 9) …… wait for your friends outside the classroom. Wait outside the building! Finally, I wish you all good luck. You can begin now! »