请问各位大神,这个题意大意和选C的原因。谢谢!
 In mountainous regions, the timberline is the highest altitude at which trees grow. In the Rocky Mountains, the current timberline is at the altitude above which growing season temperatures remain cooler than 10 degrees centigrade. Fossilized remains of trees that grew 10,000 years ago have been found 100 meters above the current Rocky Mountain timberline. Clearly, therefore, the climate of the Rocky Mountains is cooler now than it was 10,000 years ago.
  8. Which of the following is an assumption on which the argument relies?
  A. In the past 10,000 years, the only trees to have grown above today's timberline are the trees whose fossilized remains been found.
  B. No trees grew 10,000 years ago at altitudes higher than the ones at which fossilized tree remains have been found.
  C. The fossils are not of species of trees that were able to tolerate cooler growing temperatures than are the species that currently grow near the timberline.
  D. The Rocky Mountains have not eroded significantly over the past 10,000 years.
  E. The climate of the Rocky Mountains has never been significantly warmer than during the lifetime of the trees whose fossilized remains have been found.

提问者: ade6zhang 2017-08-04 23:17

1个回答

0
tonyqml 2017-08-05 08:01

文章大意:在山区,树木线(timberline)就是树木生长的最高高度(高于这个高度,树木不易存活)。在落基山脉,目前的”树木线“是摄氏温度在10度的高度,越高气温越低。然而在10000年前,在目前落基山脉树木线高度100米以上发现了一些原始树木的化石。显然现在落基山脉的气温比10000年前要冷。

前提假设:目前落基山脉“树木线”附近的树和10000年前“树木线”100米高度左右的树木是同一种“树种”,文章结论才成立。”C“ 是说 10000年前“落基山脉”树木线“100 高度的树木化石不是比目前”树木线“高度附近树木更耐寒的树种。如果不是同一种 species, 文章结论就不成立。

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