Exercise 6.5.6. Rewrite the sentences using the words given in brackets.
1. It isn’t necessary to buy a ticket (need). 2. I advise him  to be more careful (ought). 3. He couldn’t swim when he was five (able). 4. It’s possible that he will win the race (might). 5. You are not allowed to play in their garden (mustn’t). 6. It wasn’t necessary for them to repair the car (need). 7. It’s not possible for you to eat so much (can’t). 8. Do you want me to open the window (shall)? 9. It’s just possible she’s still at work (could). 10. Do you want me to help you with that (would)? 11. I don’t think she is the woman who spoke to me (can’t). 12. We don’t have to go shopping with Mum (needn’t). 13. Is it really possible that she’s 50 years old (can)? 14. It would be a good idea to tell him the truth (better). 15. I advise you to study harder (should).