Key to Exercise

1

1. has to

2. must

3. has to

4. have to

5. must

6. have to

7. had to

8. has to

9. had to

10. have to

11. must

12. have to

13. must

14. has to

15. must /have got to

2

1. needn't

2. mustn't

3. mustn't

4. needn't

5. mustn't

6. mustn't

7. needn't

8. mustn't

9. needn't

10. needn't

11. needn't

12. mustn't

13. mustn't

14. needn't

15. mustn't

3

1. must

2. can't

3. needn't

4. must

5. can't/couldn't

6. needn't

7. can't/couldn't

8. must

9. can't

10. needn't

11. must

12. must

13. must

14. needn't

15. needn't