OBLIGATION

1. It's not obligatory to wear a tie. You ... wear one.

• must

• have to

• shouldn't

• don't have to

2. Slow down or we're going to have an accident. You ... drive so fast.

• should

• ought to

• shouldn't

• oughtn't to

3. Billy : Are you going to the party?

Sally : I'm not sure. I ... go.

• don't have to

• have to

• mustn't

• might

Where's the toilet? I ... go

• have to

• shouldn't

• mustn't

• might

5. Where is your telephone? I ... use it.

• don't have to

• should

• must

• may

6. You ... do your homework on Saturday morning. That way, you'll have the rest of the weekend free.

• ought to

• shouldn't

• might

• must

7. You ... be horrible to your sister. It makes her very sad.

• must

• mustn't

• have to

• shouldn't

8. Tomorrow's holiday. We ... learn the subjects as usual and it's time to be relaxed.

• must

• have to

• mustn't

• don't have to

9. You ... take an umbrella. It might rain.

• has to

• might

• should

• shouldn't

10. If you go sailing, you ... wear a life jacket. The sea is very dangerous.

• may not

• mustn't

• might

• must