Modals for Obligation Exercises with Answers

Choose the correct answer (must, mustn't, don't/doesn't have to) to complete each sentence:

1. You Select an option: must mustn't don't have to doesn't have to forget to buy vegetables and meat. We'll make a nice recipe tonight.
2. You Select an option: must mustn't don't have to doesn't have to to turn on the air conditioner. It's an automatic system.
3. You Select an option: must mustn't don't have to doesn't have to wait for the green signal before crossing the road.
4. She Select an option: must mustn't don't have to doesn't have to take her umbrella. It is not raining.
5. We Select an option: must mustn't don't have to doesn't have to park our car in this area. It is not allowed.
6. Students Select an option: must mustn't don't have to doesn't have to wear their school uniform to class.
7. We Select an option: must mustn't don't have to doesn't have to allow ourselves to be defeated by the difficulties.
8. She Select an option: must mustn't don't have to doesn't have to to be rich to start a business.
   
9. You Select an option: must mustn't don't have to doesn't have to wait for me. I'll join you later.
10. They Select an option: must mustn't don't have to doesn't have to apologize for their behavior. It was so gross.
11. She Select an option: must mustn't don't have to doesn't have to be at the airport two hours before her flight.
    
12. You Select an option: must mustn't don't have to doesn't have to forget to lock the door before leaving the house.
    
13. They Select an option: must mustn't don't have to doesn't have to worry about the exam. They have studied enough.
    
14. You Select an option: must mustn't don't have to doesn't have to help your parents with household chores.
    
15. She Select an option: must mustn't don't have to doesn't have to buy a new dress for the party. Her old one is still in good condition.
16. You Select an option: must mustn't don't have to doesn't have to eat too much candy before dinner.
17. I Select an option: must mustn't don't have to doesn't have to do the dishes tonight. It's not my turn.
18. They Select an option: must mustn't don't have to doesn't have to smoke in this area. It's strictly prohibited.
19. These copies Select an option: must mustn't don't have to doesn't have to be clearly marked as "confidential".
20. You Select an option: must mustn't don't have to doesn't have to worry about cooking dinner tonight. I'll take care of it.