Choose the correct alternative for each sentence.

Correct Alternatives

1. It's a good idea to get a good night's sleep before an exam.
   a) You must get a good night's sleep before an exam.
   b) You should get a good night's sleep before an exam.
2. Use of mobile phones in the classroom is forbidden.
   a) You mustn't use your mobile phone in the classroom.
   b) You don't have to use your mobile phone in the classroom.