15. A: A. Watch out! There's a car coming. - B: Thank you. B. Don't do that. 16. A: Honey, you ate too many sweets today. A. You shouldn't eat that kind of sweets. C. If you do that, your teeth may be hurt. 17. I think we should these envelopes. A. reuses 18. My future house will A. have 19. A. Where 20. If we A. protect B. reuse C. Don't sleep. D. Listen! - B: Yes, Mom. C. to reuse eight rooms and 4 robots. B. has C. to have did you watch on TV last night? - I watched the Fox Teacher. B. What C. When our forest, we will help our planet. B. protected C. to protect B. Don't do that again. D. The sweets are tasty. D. reused D. having D. How D. protects