1. They / to do a science project this year
2. We / shout in class
3. I / forget my mobile phone
4. I / work on Saturdays
5. You / drink this water. It will make you ill
6. I / learn all these words for tomorrow's lesson
7. She / finish this report by tomorrow
1. don't have to
2. mustn't
3. don't have to
4. don't have to
5. mustn't
6. don't have to
7. doesn't have to