The gallery is free. You don’t have to pay.
You mustn’t wear jeans to school. It’s forbidden.
The speed limit is 100 km/h. You mustn’t drive faster.
Your working hours will be 8-4 Monday to Friday. You don’t have to work at weekends.
That river is dangerous. You mustn’t swim in it.
You don’t have to do this exercise. It’s not necessary.
We don’t have to take the tent. Mike will do it.
I mustn’t forget to type this letter. It’s very important.
You don’t have to take an umbrella. It isn’t going to rain.
We don’t have to hurry. There’s a lot of time.
You mustn’t drop those glasses. They’ll break.
I mustn’t forget my keys or I won’t get in.