39. Most archaeologists have held that people first reached the Americas less than 20,000 years ago by crossing a land bridge into North America. But recent discoveries of human shelters in South America dating from 32,000 years ago have led researchers to speculate that people arrived in South America first, after voyaging across the Pacific, and then spread northward.

Which of the following, if it were discovered, would be pertinent evidence against the speculation above?

A. A rock shelter near Pittsburgh, Pennsylvania, contains evidence of use by human beings 19,000 years ago.

B. Some North American sites of human habitation predate any sites found in South America.

C. The climate is warmer at the 32,000-year-old South American site than at the oldest known North American site.

D. The site in South America that was occupied 32,000 years ago was continuously occupied until 6,000 years ago. B

E. The last Ice Age, between 11,500 and 20,000 years ago, considerably lowered worldwide sea levels.

做完题目,再仔细一想, B中说发现北美的居民比南美的还早...的确削弱了原文的结论.

那么是不是也同时削弱了原文的提干, 比南美还早的话, 就不可能是20000年前到达的拉,应该还要早啊....

这样把原文中的提干也一起削弱也可以么?

很有趣！

我再想是不是people first reached跟human habitation不一样。

前者是指外人进来，後者可能指当地就已经有人烟

我昨天刚好也做到，看到B连题干都削弱了，直接跳过。

不过后来思考了一下，觉得是这样的：

考古学家一直认为最先到达北美的时间是2万年前，可想而知，是考据证据推出来的。这时，你要是发现了一个北美土著的居住点，它存在的时间比南美任何一个人都长的话，显然考古学家也会认为人类到达北美的时间比南美早，可以认为并不是对题干的削弱，而是提供了新的信息，这点在GMAT考试里是允许的。

注意题目的语气：if it were discovered 说明可能发现的证据，题干中是发现了南美的证据得出了推论，如果你发现了北美的证据来驳倒它也是允许的，嗯