阅读理解。 Birds Journeys The wish that shows birds to begin their journeys, and the highly exact feeling of direction shown by traveling birds, stay among the most puzzling mysteries of science. The Arctic tern and the golden plover are two examples of these unusual birds. In the north during the springtime, traveling birds return to the Arctic (北极) from southern areas. The longest journey is made by the unbelievable Arctic tern. This amazing bird is no larger than a crow (a kind of bird) , but its body surface (outside) is more updated. The tern is called the long-distance champion of the bird world, often traveling 23,000 miles a year between West Africa and the Arctic. Such journeys take weeks, with stops for food and rest. There are no rests, however, for the golden plover, a non-stop flyer among Arctic birds. The plover's journey is like that of a land plane over water, since the plover cannot land on the water to rest. Without stopping, the golden plover flies 2,000 miles from Hawaii to Alaska or from South America to Nova Scotia and northern Canada. This little bird (only eleven inches) is fat and strong when traveling north, but is thin and weak when it arrives after fighting ocean winds for sixty or more hours. 1. Look at the first paragraph. What does the underlined word ' mysteries 'mean? [     ] A. 秘密 B. 神秘 C. 机密 D. 隐秘 2. What do the tern and the plover have in common? [     ] A. Their bodies are updated. B. Their bodies are fat and strong. C. They travel great distances. D. They travel the same amount of time. 3. From the second paragraph, we get to know that the tern _______. [     ] A. is as big as a crow B. is an Arctic bird C. travels a long distance D. travels to another land 4. After traveling north, why does the golden plover become thin? [     ] A. It stops once for food. B. It can fly better and faster. C. It is no bigger than a crow. D. It has to fly against the ocean wind.