20. It ______________ when I left Ireland.  
A. was rain                B. was raining                C. is raining                D. raining 21. Andrea lives next door, so we ____________ see her.
A. never                B. often                  C. rarely  D. seldom 22. We should avoid dumping waste ____ lakes and rivers to reduce water pollution.
 A. on                        B. into                        C. out                        D. by
23. Americans throw ___________ twenty-eight and a half million tons of plastic in landfills every year.
A. in                         B. at                         C.to                         D. away
24. Residents in tall buildings in Ha Noi ran _____ their homes in fear.
A. out of                 B. on                         C. to                         D. out
25. Con Dao National Park ______ a rich habitat for marine life.
A. releases  B. reduces    C. provides    D. reuses
26. The roads were slippery ___________ it started to rain.
A. so                        B. as soon as                 C. when                D. before
27. My grandmother ____________ goes to the market to buy food. She goes there every day.  
A. always                B. never                C. rarely                D. sometimes 28. Do you like ____________ products?
A. home-growing         B. home-grew                C. home-grown        D. home-grow 29. _______ trees and burning forests destroy a lot of wildlife habitats.
A. Watering    B. Cleaning up  C. Planting   D. Cutting down
30. Do you know that ____ can cause pollution?
A. littering    B. releasing    C. protecting D. keeping
31. You can _______ bargain at the supermarket because the prices are fixed.
A. always    B. often    C. never  D. sometimes
32. There were only a few houses left standing _____ the tornado hit.
A. after    B. before    C. as soon as D. until
33. The shuttle bus ____ every 15 minutes to take customers to the parking lot.
A. will leave   B. leaves    C. left   D. was leaving
34. We _____ home economics next semester. We have music instead.
A. didn’t have  B. won’t have  C. don’t have D. weren’t having 35. The announcement says that the sale _______ for just two hours, from 17:00 to 19:00 tomorrow.
A. lasts    B. will last    C. lasted  D. last
36. Phong: My uncle called this morning. A flood destroyed his house.       Mark: ________
A. I’m glad.          C. You’re welcome.
B. I’m sorry to hear that.      D. You’re very kind.
37. What were you doing when the volcano _______ ?
A. erupted    B. erupt    C. erupts  D. was erupting