Rewrite the following sentences so as not to change their meaning. MODALS/PERFECT MODALS 1. Possibly she isn't John's sister. (MAY) 2.Perhaps we will go on a picnic next month. (MAY) 3. She was able to read when she was two. (COULD) 4. It is not necessary for you to pay the bill. (NEED) 5. I am certain that they have already left. (MUST HAVE) 6. I was in the habit of going for a walk every morning when I was in Singapore. (USED TO) 7. It is probable that he will pass his driving test easily. (MAY) 8. Perhaps he forgot to bring the book. (MIGHT) 9. Nobody answered the phone; I'm sure they have gone out. (MUST HAVE) 10. I am certain that he is over sixty. (MUST) 11. It is not necessary for them to wear uniforms. It's not our school rule. (HAVE TO) 12. He has the ability to use his left leg to score goals. (CAN) 13. You are advised to revise the lessons before the exam. (SHOULD) 14. It is prohibited that children watch this horror movie. (MUST) 15. Children have the obligation to take care of their old parents. (OUGHT TO)