Grammar worksheet teaching the use of "must" and "mustn't" with practical examples and exercises.

To solve this worksheet, we need to decide if each sentence describes something necessary and good for a healthy life (use must) or something bad and unnecessary that should be avoided (use mustn't).

Here is the step-by-step logic for each question:

1. get lots of exercise: Exercise is good for you. -> must (Already done in the example)
2. smoke cigarettes: Smoking is bad for your health. -> mustn't (Already done in the example)
3. have some good friends: Having friends makes you happy and healthy. -> must
4. relax sometimes: Relaxing helps reduce stress. It is important. -> must
5. sleep all day: Sleeping too much is lazy and unhealthy. -> mustn't
6. eat lots of vegetables: Vegetables are very healthy. -> must
7. get angry easily: Getting angry often is bad for your mood and health. -> mustn't
8. watch too many hours of TV: Watching "too many" hours is bad for you. -> mustn't
9. stay up very late at night: You need rest; staying up late is bad for sleep. -> mustn't
10. get enough sleep: Sleep is essential for health. -> must
11. read some good books: Reading is a good habit for your brain. -> must
12. eat lots of cheeseburgers and fries: This is junk food and not healthy. -> mustn't
13. drink lots of water: Water is essential for your body. -> must
14. forget to smile and say 'hello' to people: Being polite and friendly is good. Forgetting to do it is bad. -> mustn't
15. always think about problems: Worrying all the time is stressful. -> mustn't

Final Answer:
1. must
2. mustn't
3. must
4. must
5. mustn't
6. must
7. mustn't
8. mustn't
9. mustn't
10. must
11. must
12. mustn't
13. must
14. mustn't
15. mustn't