chứng minh 10^28 +8 chia hết cho 72 so sánh A=1+2+2^2+2^3+2^4+...+2^2001+2^2002 với B=2^2003

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PART 4 QUESTIONS 21-27 Read the article about some birds.Are sentences 21-27 ‘Right’ (A) or ‘Wrong’ (B)? ‘Doesn’t say’ (C).For questions 21-27, mark A, B or C on the answer sheet. CANADA GEESE Canada Geese are large blue and white birds. When autumn arrives, they have to fly south where the weather is warmer. The winters are so cold in Canada that the birds die if they stay there. Last spring, Bill Lish man found sixteen young Canada Geese on his farm. They hadlost their parents. Bill thought, These young birds won’t know what to do in the autumn.’ Bill had a small plane and he decided to teach the bird s to follow him. All through thesummer, he went on short trips in his plane and the young geese flew after him. When the cold weather arrived in autumn, Bill flew to Virginia in the United States. 600miles south of his home in Canada. The geese followed him all the way. Bill left the geese in Virginia and he returned home. This spring, Bill was waiting for the birds to come back. They didn’t arrive, so Bill flewto Virginia to get them. He looked for them for two weeks but he couldn’t find them. When he arrived back home, Bill found the geese waiting for him. They had found theirway home without him! 21 Bill Lishman is a farmer. A Right B Wrong C Doesn’t say 22 Bill lives with his parents. A Right B Wrong C Doesn’t say 23 Bill carried the geese in his plane. A Right B Wrong C Doesn’t say 24 This was Bill’s first visit to Virginia. A Right B Wrong C Doesn’t say 25 Bill wanted the geese to stay at his home for the winter. A Right B Wrong C Doesn’t say 26 Bill stayed in Virginia all winter. A Right B Wrong C Doesn't say 27 The geese returned to Canada in the spring. A Right B Wrong C Doesn’t say EXAMPLE 0 Winters in Canada are too cold for Canada Geese. A Right B Wrong C Doesn’t say help mee

III. REWRITE : 1. If he doesn’t take more care, he’ll have an accident. ->Unless . ……………………………………………………………….. . 2. The crops will be ruined if it doesn’t rain soon. ->Unless ......... . …………………………………………………………………….. 3. Unless the weather is fine, we’ll stay at home. -> If . . . . …………………………………………………………………….. 4. I can’t go with you unless I get my work finished. ->If ............... . …………………………………………………………………….. 5. If you don’t leave on the 15th , you’ll get home late for your mother’s party. -> Unless............ . ……………………………………………………………….. 6. Tom never does anything unless his father tells him what to do. ->If ............ . ………………………………………………………….. 7. Don’t take this job if you don’t really want it. ->Unless ............ . ………………………………………………………………….. 8. If she does nothing to prepare for the test, she will get bad marks. ->Unless ......... . ……………………………………………………………….. 9. You can’t visit the United States unless you get a visa. ->If ............... . …………………………………………………………………….. 10. Unless you remember our address, you can find it in the phone book. ->If ...................... . …………………………………………………………………..