Put in 'mustn't'or 'don't/doesn't have to:
1.We have a lot of work tomorrow. You......... be late.
2.You.......... tell anyone what I just told you. It's a secret.
3.The museum is free. You........pay to get in.
4.Children..........tell lies. It's very naugthy.
5.John's a millionaire. He........go to work.
6.I.........do my Washington, because my mother does it for me.
7.We.........rush. We've got plenty of time.
8.You..........smoke inside the school.
9.You can borrow my new dress but you........get it dirty.
10.We.............miss the train. It's the last one tonight.
11.She..........do this work today,because she can do it tomorrow.
12.I...........clear the floor today, because I cleaned it yesterday.
13.We.........forget to lock all the doors before we leave.
14.We.........stay in a hotel in London, we can stay with my brother.
15.I.........spend too much money today. I've only got a little left.
16.They.........get up early today, because it's Sunday.
17.I.........eat too much cake, or I'll get fat!
18.We.......be late for the exam.
19.You..........tidy up now. I'll do it later.
20.He.........cook tonight because he's going to a restaurant.