20. I ………………. Sydney Harbour twice, so this time I think I ………………. to a different place. A. have visited - will go B. have visited - will be going C. visited - will go D. visited - will be going 21. Water ………….. in the lake has made the fish die. A. pollution B. pollute C. polluted D. polluting 22. When we ………… back to our home village last month, it ……………… so much. A. had come - changed B. came - had changed C. came - has changed D. had come - has changed 23. She ……………… in that town for 20 years by the time that historic earthquake A. had live – occurred B. has lived – occurred C. had lived - occur D. had lived – occurred 24. Some tents ……………… so that children and old people could sleep in. A. was set up B. were set up C. set up D. setted up 25. People in Japan ……………… how to survive in an earthquake. A. have been taught B. are taught C. were taught D. had been taught