Mustn't / don't have to

Exercises: modal verbs

01.- You speak Spanish to travel.
02.- Children chat in class.
03.- I study this weekend.
04.-You be late for school.
05.- You smoke in the car.
06.- You be young to dance.
07.- You be sixteen to ride a bike.
08.- People step on the flowers.
09.- You talk with your mouth full.
10.- You be fat to do exercise.
11.- We walk the dog every hour.
12.- You tear pages out of books.