Ответ:
1.You must tidy up your room.
2.You mustn't smoke.
3.You must do your homework.
4.You mustn't play with fire.
5.You must be home on time.
6.You mustn't cheat in a test.
7.You mustn't turn the music too loud.
8.You must help in the house.
9.You mustn't annoy your little sister.
10.You mustn't bite nails.
Объяснение:
must-должен (делать)
mustn't-не должен (делать)