1 Students may miss some lessons.
2 You should write her a letter.
3 I must lose weight.
4 You have to (don`t have to)take part.
5 You needn`t go to school without your books.
6 We don`t have to book seats.
7 We couldn`t stay.
8 You ought to drive carefully.
9 You don`t have to come ...
10 She can`t be...