1. It's cold. You should/shouldn't turn on the fan. 2. You ought not to/ought to do homework before you go out with your friends.  3. You should/shouldn't eat plenty of fruit or vegetables every day in order to keep healthy. 4. You must/mustn't eat in the class. 5. You ought to/ought not to drink a lot of water every day. 6. I must/have to submit my homework before 12 o'clock because the deadline is 12 o'clock. 7. I must/have to stay at home to take care of my children. 8. My friend says: "You don't have to/mustn't drink champagne. You can have a coke or fruit juice instead.  9. You don't have to/mustn't drink if you're going to drive afterwards.  10. You don't have to/mustn't pick up Tom at the airport because Judy will 

Cách làm:

1. Đọc kỹ câu hỏi và xác định các từ khóa trong câu

2. Xác định nghĩa của các từ "should", "ought to", "must", "have to", "don't have to", "mustn't", "ought not to" trong câu hỏi

3. Sử dụng nghĩa của từ khóa đó để xác định câu trả lời chính xác cho mỗi câu hỏi

Câu trả lời:

1. It's cold. You should turn on the fan.
2. You ought to do homework before you go out with your friends.
3. You should eat plenty of fruit or vegetables every day in order to keep healthy.
4. You mustn't eat in the class.
5. You ought not to drink a lot of water every day.
6. I have to submit my homework before 12 o'clock because the deadline is 12 o'clock.
7. I must stay at home to take care of my children.
8. My friend says: "You don't have to drink champagne. You can have a coke or fruit juice instead.
9. You mustn't drink if you're going to drive afterwards.
10. You don't have to pick up Tom at the airport because Judy will.

I must submit my homework before 12 o'clock because the deadline is at 12 o'clock.

You ought to drink a lot of water every day to stay hydrated.

You mustn't eat in the class as it is against the school rules.

You should eat plenty of fruit or vegetables every day in order to keep healthy.