Choose the correct options.

1.rabbits can't / must fly.

2.you could / mustn't forget your book. you'll need it.

3.last year i must / had to learn chinese.it was really difficult.

4.i've been learning english for seven years,so i can/ have to speak it quite well now.

5.you should / mustn't try harder in class.

6.my mum can't / couldn't swim when she was a child.

7.you mustn't / don't have to wash your hair every day. twice a week is enough.

8.we had to / could see the sea from the house where we stayed last summer.

9.she must / shouldn't remember her hockey stick today because she's playing in a match.

10.i have to / can't study tonight because we have an important test tomorrow.

11.you can / shouldn't swim in the lake. it's very danderous.

12.my grandad mustn't / didn't have to study science at school.