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英国境内有浅色和黑色两种桦尺蛾，它们都喜欢栖息在树干上，但是，在工业污染区，黑色桦尺蛾占多数，浅色桦尺蛾占少数。请用达尔文的自然选择理论对此进行解释。

答案

在工业污染区黑色桦尺蛾体色与周围环境一致，不易被天敌发现而生存下来，大量繁殖，所以数量多，浅色桦尺蛾的体色在黑环境中目标最显著，易被天敌发现而不易生存下来，所以数量少。

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Part 2


Questions 9-18


Read the following passage and answer questions 9-18.
1. Most young people enjoy some forms of physical activity. It may be walking, cycling or swimming, or in winter, skating or skiing. It may be a game of some kind football, golf, or tennis. It may be mountaineering.
2. Those who have a passion for climbing high difficult mountains are often looked upon with astonishment. Why are men and women willing to suffer cold and hardship, and to take risks on high mountains This astonishment is caused probably by the difference between mountaineers and other forms of activity to which men give their leisure.
3. Mountaineering is a sport and not a game. There are no man-made rules, as there are for such games as golf and football. There are, of course, rules of a different kind which would be dangerous to ignore, but it is this freedom from man-made rules that makes mountaineering attractive to many people. Those who climb mountains are free to use their own methods.
4. If we compare mountaineering with other more familiar sports, we might think that one big difference is that mountaineering is not a "team game". We should be mistaken in this. There are, it is true, no "matches" between "team" of climbers, but when climbers on rock face linked by a rope on which their lives may depend, there is obviously teamwork.
5. The mountain climber knows that he may have fight forces that are per and more powerful than man. He has to fight to against the forces of nature. His sport requires high mental and physical qualities. A mountain climber continues to improve in skill year after year. A skier is probably past his best by the age of thirty, and most international tennis champions are in their early twenties. But it is not unusual for a man of fifty or sixty to climb the highest mountains in the Alps. They may take more time than young man, but they probably climb with more skill and less waste of effort, and they certainly experience equal enjoyment.

Questions 9-13


·For questions 9-13. choose the best title for each paragraph from below.
·For each numberedparagraph (1-5), mark one letter (A-G) on the Answer Sheet..
·Do not mark any letter twice.
  • A. Mountaineering is different from golf and football.
  • B. Mountaineering is treated as a team sport.
  • C. The requirements needed for climbers.
  • D. Many young people enjoy some forms of physical activity.
  • E. A mountain climber’s skill is not limited by his age.
  • F. The reason why people enjoy climbing mountains.
  • G. Mountaineering is a sport rather than a gam

Paragraph 1: ______
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单项选择题

重症肌无力的辅助检查结果哪项有误（）

A.血常规检查正常

B.胸部X线和CT平扫可发现胸腺瘤

C.脑脊液常规检查正常

D.尿常规检查正常

E.电生理检查神经肌肉传递正常
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