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板凳
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发表于 2009-4-16 13:19:00
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哦，呵呵，好哈。鄙人浅见，错了勿见怪。
2004.10 section D No. 17：Climatologists believe they know why Earth has undergone a regular sequence of ice ages beginning around 800,000 years ago. Calculations show that Earth's orbit around the Sun has fluctuations that coincide with the ice-age cycles. The climatologists hypothesize that when the fluctuations occur, Earth passes through clouds of cosmic dust that enters the atmosphere; the cosmic dust thereby dims the Sun, resulting in an ice age. They concede, however, that though cosmic dust clouds are common, the clouds would have to be particularly dense in order to have this effect.
Each of the following, if true, would lend support to the climatologists' hypothesis EXCEPT:
A. Earth did not pass through clouds of cosmic dust earlier than 800,000 years ago.
B. Two large asteroids collided 800,000 years ago, producing a tremendous amount of dense cosmic dust that continues to orbit the Sun.
C. Earth's average temperature drops slightly shortly after volcanic eruptions spew large amounts of dust into Earth's atmosphere.
D. Large bits of cosmic rock periodically enter Earth's atmosphere, raising large amounts of dust from Earth's surface.
E. Rare trace elements known to be prevalent in cosmic debris have been discovered in layers of sediment whose ages correspond very closely to the occurrence of ice ages.
ABC都很好理解，AB 从时间上，C从dust的角度支持原文。我的问题在于D和E选谁。答案给的是D。
我发现我选E是因为我对 E 选项的错误理解。
以前我理解的是，一种trace elements (the elements that are known to be prevalent in cosmic debris) 很少被发现 （this kind of elements correspond to the occurrence of ice age）。这种理解是削弱原文的，好像是答案。
但其实 E 选项的正确理解应该是， 很稀有的trace elements被发现了，这种elements correspond to the occurrence of ice age。这种理解就是支持原文的。
E选项之所以应该是后一种理解而不是前一种理解，是因为rare的词性，如果是第一种理解的话应该用rarely，原文出现的rare应指第二种理解。
而D选项说的是dust from earth's surface应该和cosmic dust不是同一回事，而且large amounts也不知道究竟多大。所以选D。
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发表于 2009-4-14 14:39:00
