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nt home of all modern birds was the tropic areas. There they lived so well that the region became overcrowded. Many species had to move northward.During the summer, these birds found plenty of room and food. In winter, however, food became scarce and they had to return to the south. A newer theory is that increasing daylight stimulates certain glands（腺） in the bird''s body and prepares it for migration. One scientist is able to make birds migrate in midwinter by exposing them for two months to artificial daylight. Recoveries of marked birds indicate that they fly north as soon as they are set free. The conclusion is that the urge to migrate is determined by changes in the bird''s body which take place under seasonal changes in the length of daylight. This theory would account for the fact that not all birds migrate at the same time. Each species seems to have its own schedule. The theory would also account for the regular time and routes of migration. Birds arrive at a given place year after year. Unfavorable weather delays them only a few days. Total hours of daylight, rather than weather, start them on the way. How birds find their way to the same place year after year and why they follow their own particular route are still mysteries. They evidently do not follow known landmarks（地面标志）,for many young birds migrate alone without the help of experienced adults. We can conclude from the first paragraph that ______. A.during the Ice Age, the whole Europe was covered with iceB.the south used to be the homelands of all birdsC.scientists can confidently explain why birds migrate nowD.migration of birds can be explained by the change of ice on earth. 参考答案： D migration of birds can be explained by the change of ice on earth.----------------------------------------12、 The birds mentioned in the third paragraph fly north in midwinter because ______. A.they are specially trained by a scientistB.they are affected by seasonal changesC.there is a change in their body temperatureD.they are exposed to extra daylight 参考答案： D they are exposed to extra daylight----------------------------------------13、 The phrase"account for"（Line 2, Para. 4） most probably means ______. A.indicateB.explain C.proveD.provide 参考答案： B explain----------------------------------------14、 The best title for the passage is ______. A.Different Accounts of MigrationB.Migration and WeatherC.New Discovery of Bird MigrationD.Routes of Bird Migration 参考答案： A Different Accounts of Migration----------------------------------------15、 Which of the following can NOT be inferred from the passage? A.Birds do not migrate at the same time.B.Birds usually follow regular routes of migration.C.Each species has a special reason for migration.D.Birds migrate to their own particular places every year. 参考答案： C Each species has a special reason for migration.----------------------------------------1 A.The essay test.B.How teachers test their students.C.How students write their essays. D.The objective test. 参考答案： The objective test.----------------------------------------2 A.it shows more about the student''s understanding of the subjectB.it tests the student''s knowledge of the material as well as his expression of ideas.C.it gives each student a fairer chanceD.its scoring may be influenced by the examiner''s feelings 参考答案： it shows more about the student''s understanding of the subject----------------------------------------3 A.students may receive a lower score in an essay testB.another examiner usually gives the ans
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