Exercise 3

1. You musn't tell lies.

2. Studnet musn't cheat during the test.

3. A person don't have to war so much money to have a happy live.

4. You musn't play with matches.

5. I've already finished all my homework, so I don't have to study late tonight.

6. I mustn't forget to take my pens and my pencils with me.

7. You don't have to introduce me to her. I have already known her.

8. Drivers musn't drives fast in the city centre.

9. You don't have to go to the concert if you don't want to. 

10. In order to be a good student, you mustn't be so untidy and lazy. 

11. They don't have to work on Saturday.

12. Visistors mustn't feed the animals.

13. Tim doesn't wear unifrom at school.

14. You mustn't touch that switch.....

15. Don't make so much noise. We musn't wake the baby.

16. There's a lift in the building, so I don't have to climb upstair.

17. Staff mustn't smoke when serving customers.

18. Sally is extremly rich. She don't have to work. 

19. I don't want anyone to know about our plan. You mustn't tell anyone. 

20. You don't have to be a good player when you enjoy a game of tennis. 

3. WHY - BECAUSE

1. - Because he's a careless driver, he had accidents so often. 

    - He had accidents so often because he's a careless driver.

2. He looked happy because he passed the test.

Have a nice day :3