Mustn't or don't have to ...!

Mustn't or don't have to

Tick the correct sentence in each pair..

1 a The performance starts at 8 pm so we don't have to be late.
   b The performance starts at 8 pm so we mustn't be late.
2 a You mustn't tell anyone because it's a secret
   b You don't have to tell anyone because it's a secret

Mustn't is used to say that something is not allowed: 
You mustn't smoke in here. (it's not allowed)
We mustn't shout. (the baby is asleep, we'll wake her up)
Don't have to is used to say that it is not necessary to do something: 
I'm on holiday! I don't have to work for two weeks.
We don't have to whisper. (there's no one else here)
Underline the correct words.
1 We don't have to / mustn't pay to get in. It's free.
2 Be quiet! You mustn't / don't have to talk in the library.
3 We mustn't / don't have to forget our tickets for the train, or we'll have to pay a fine.
4 You mustn't / don't have to wear a uniform. You can wear whatever you like.
5 Tell Ahmed he mustn't / doesn't have to argue with his boss again, or he'll get the sack.
6 You don't have to / mustn't tidy your room. I tidied it this morning.
7 I mustn't / don't have to leave early. If I miss my bus I can walk home.
8 We mustn't / don't have to be late. They lock the doors after midnight. 

 

Answer Key:1.1: b
1.2: a
2.2: mustn't
2.3: mustn't
2.4: don't have to
2.5: mustn't
2.6: don't have to
2.7: don't have to
2.8: mustn't