Вставьте подходящий модальный глагол (must/may/can).

1. You (must/may/can) not smoke here.
2. (Must/may/can) you hear that strange noise?
3. He (must/may/can) come today or tomorrow.
4. My little brother (must/may/can) count to ten.
5. This incident (must/may/can) have serious consequences.
6. You (must/may/can) have a valid permit to enter.