can/mustn't.

1. You mustn't talk loudly in the library.
2. You must fasten your seatbelt in the car.
3. The concert starts at 7 p.m. We mustn't be late.
4. You mustn't take photos in the museum. It's forbidden.
5. I have a very important exam tomorrow. I must study hard tonight.
6. The pool is deep here. You mustn't swim if you are a child. It's dangerous.