Question

Exercise 18. Fill in the blanks with mustn't or ought not to
1. You ... ... take any medicine without the doctor's advice.
2. You .. ... keep these library books with you for more than a week.
3. WE......... leave the car unlocked.
4. YOU........... go inside without signing the entry register.
5. We........ throw rubbish in the street. ​

Answer 1

1. Mustn’t
2. Ought not to
3. Mustn’t
4. Mustn’t
5. Mustn’t


I feel like mustn’t fits all the sentences but I’m not quite sure.

Answer 2

Answer:

you are right.............