Ответ:
- C Must I go outside, please?
- B mustn't You mustn't drive on campus. It's forbidden.
- A must The rules say we must keep our rooms tidy.
- B can't I'm afraid you can't go out now. It's too late.
- B mustn't You mustn't put posters on the wall. It's forbidden.
Ответ: см.выше
Ты отлично справляешься! Продолжай в том же духе, и у тебя все получится!