Употребите must/mustn`t.
7.We _________ wear a uniform.
8.We _________ be late.
9.We _________ listen to the teacher.
10.We _________ do our homework.
11.We _________ drop litter in the class.
12.We _________ pick the flowers from the garden.
13.We _________ keep off the grass.
14.We _________ keep your dog on a lead.
15.We _________ make our bed.
16.We _________ put out the fire.