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标题: GWD11-Q41 [打印本页]

作者: viviansecret 时间: 2009-8-30 10:53
标题: GWD11-Q41

Charcoal from a hearth site in Colorado, 2,000 miles south of Alaska, is known to be 11,200 years old. Researchers reasoned that, since glaciers prevented human migration south from the Alaska-Siberia land bridge between 18,000 and 11,000 years ago, humans must have come to the Americas more than 18,000 years ago.

Which of the following pieces of new evidence would cast doubt on the conclusion drawn above?

A. Using new radiocarbon dating techniques, it was determined that the charcoal from the Colorado site was at least 11,400 years old.

B. Another campsite was found in New Mexico with remains dated at 16,000 years old.

C. A computer simulation of glacial activity showed that it would already have been impossible for humans to travel south overland from Alaska 18,500 years ago.

D. Using new radiocarbon dating techniques, it was proved that an ice-free corridor allowed passage south from the Alaska-Siberia land bridge at least 11,400 years ago.

E. Studies of various other hunting-gathering populations showed convincingly that, once the glaciers allowed passage, humans could have migrated from Alaska to Colorado in about 20 years.

答案：D。这道题我选的是E。不是很明白。。。请nn指教下吧：）

[此贴子已经被作者于2009/8/30 10:53:34编辑过]

作者: Winnieny 时间: 2009-10-20 07:31
愚见：
since glaciers prevented human migration south from the Alaska-Siberia
land bridge between 18,000 and 11,000 years ago, humans must have come
to the Americas more than 18,000 years ago.题目说冰川让人们无法在 18,000 and 11,000 years ago这段时间跨越Alaska-Siberia，所以他们肯定是18000年前来的美国。
D选项说有一种新技术已经证明ice-free corridor可以让人们在11，400年前就跨越Alaska-Siberia。那这些人也许在11，400年前就来美国了，而不是18000年前来的。

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