1. The children must be there ________ 7.30 to 10.30. 2. ” Why not join with us to the countryside this weekend? “ _ “ ________. ” 3. Don’t let the children __________with matches. 4. As a student, you ___ hard to please your parents. 5. It is safe _ medicine in locked cupboard. 6. The children are old enough to take care of _____. 7. They arrived home _________ after a long distance journey. 8. Heat gradually ______________ Vitamin C. 9. Don’t let your little brother play with ballpoint pen. They can ___ him. 10. No one helped Nam clean his bicycle. 11. It isn’t necessary for you to go to school so early. 12. It is not a good idea for you to put so much salt in the soup. 13. Hard work always brings ___________ . 14. You have to keep all dangerous objects ____ children’s reach. 15. Every year, factories release thousands of tons of poisonous ____________into the atmosphere 16. There is a refrigerator _____________the right corner of the room 17. Keeping medicine in unlocked cupboards is not safe. 18. You have / before children /the bath water / to check/ get in/ temperature 19. I go to school by ____________ bike 20. Yesterday I came to school on time _________the traffic was terrible.