3 Fill in must, mustn't or can't.

Grammar - Exercise 3: Must, Mustn't, Can't

Here are the sentences completed with the correct modal verbs:

A.G. Baillie Secondary School Rules

1. You mustn't run in the halls at school.
2. You mustn't be mean to your classmates.
3. You must treat your teachers with respect.
4. You must do your homework every night.
5. You mustn't talk in class.
6. You mustn't eat or drink at your desk.
7. You must be on time.
8. You must always wear your school uniform.

Explanation:

• Mustn't is used for prohibitions (things you are not allowed to do).
• Must is used for rules and obligations (things you are required to do).