1. ______ ari is one of the many problems we have to solve
A. Pure B. Polluted C. Dust D. Pleasant
2. I'll be in trouble if I ______ my passport.
A. lose B. will lose C. lost D. would lose
3. We can eat at home or, ________ you prefer, we can go to a restaurant.
A. when B. whether C. if D. which 4. If it is raining this evening, I_________. A. will go out B. don’t go out C. go out D. won’t go out 5. Minh’s English is excellent. He speaks________. A. perfectly English B. English perfectly C. perfect English D.English perfect 6. I’m disappointed _________ people have spoiled this area. A that B. when C. if D. how 7. He ________ to find a job but he had no luck. A. hardly tried B. hard tried C. tried hardly D. tried hard 8. We couldn’t go on a picnic as planned __________ it was raining. A. however B. but C. because D. so 9. If he ________ hard today, can he have a holiday tomorrow? A. works B. will work C. worked D. would work 10. ________we were tired, we sat down beside the stream. A. Because of B. If C. As D. And 11. He _________to find a job, but he had no luck. A. tried hard B. hardly tried C. tried hardly D. try hardly 12. Solar energy doesn’t cause __________. A. pollution B. polluted C. pollute D. pollutant 13. Are you lookingh forward ___________ my letter ? A. to see B. to seeing C. saw D. seeinga) vì sao ở người có những phương pháp nghiên cứu di truyền riêng? đó là nhưng phương pháp nào ?
b) trẻ đồng sinh cùng trứng và khác trứng khác nhau cơ bản ở điểm nào? Phương pháp nghiên cứu trẻ đồng sinh có ý nghĩa gì? Cho ví dụ về trẻ đồng sinh ?