求教：OG-39 一直困惑的问题

每次做这个题都想不通，终于忍不住上来问一下！

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.

答案是B。但是总觉得B否定了原文的条件。如果真有North sites predating and sites found in South,那根据原文条件就是早于32，000年前。但是首句又说“Most archaeologists have held that people first reached the Americas less than 20,000 years ago”。这个不是矛盾了吗？

题设虽然那么说了,但是没说那种说法就是对的啊,第一句是most archaeologistsr认为的一种观点而已，如果他是对的了，就不会有recent　discovery去驳斥它了。而且你仔细看看问题，就是让你来找一个evidence来反驳上面的观点。就是说明题目中谈到的东西未必都是定论，只要有一个更有说服力的考古证据，就有可能把它驳倒

恩。。有道理

这个题目的险恶之处在于反驳speculation要用到开始观点的一部分，害我以为就要选个支持原来观点的……每做一遍就被它绕一次

偶以为不要想太复杂。结论是先到南美，再到北美，要反驳，就找有关先到北美再到南美的证据，B正好给你提供了这个削东东的利器。管它怎么削弱，反正是削了。

我原来也和你有一样的问题。可是看到这个题目的问法后，疑问就消除了。题目问：Which of the following, if it were discovered, would be pertinent evidence against the speculation above。虚拟语气表明选项中的证据目前还没有被发现。因此，大多数考古学家目前所持的观点并没有错误。即Most archaeologists have held that people first reached the Americas less than 20,000 years ago”。如果哪天这个证据真被发现了，那么考古学家自然会该变他们的观点。原文的首句话是建立在真实证据的基础上的，而B只是一种假想。

以前一直认为是2000年前，先到的北美

后来发现南部有3200年的东西，就猜想是先到的南美再到的北美。

问削弱文章的猜想

B：“some”重要，一些北方的地方比南方的任何东西都要早，那这样的猜想就不成立

some的出现没有否定以前的看法。

但是some一旦出现，就把first给反驳掉啦。毕竟first是个极端词。

martinaquan说的也有道理啦。不过我就是通过这题得出：削弱结论不一定＝支持结论反对的东西（虽然大多数情况下是这样）

Most archaeologists have held that people first reached the Americas less than 20,000 years ago by crossing a land bridge into North America.

这是以前的想法

题目问：, if it were discovered, would be pertinent evidence against the speculation above

如果发现的话，可以理解为虚拟，即其实没有发现，如果发现了的话

B：就是这个虚拟的事实。如果它真的被发现了，那么“以前的想法“作古，同时，以以前的想法加上另外一些证据作出的推测，也就被weaken。

终于明白了~