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标题: GWD-4-31 [打印本页]

作者: tingting520    时间: 2010-8-31 06:54     标题: GWD-4-31

Frobisher, a sixteenth-century English explorer, had soil samples from Canada's Kodlunarn Island examined for gold content. Because high gold content was reported, Elizabeth I founded two mining expeditions. Neither expedition found any gold there. Modern analysis of the island's soil indicates a very low gold content. Thus the methods used to determine the gold content of Frobisher's samples must have been inaccurate.

Which of the following is an assumption on which the argument depends?

A. The gold content of the soil on Kodlunarn Island is much lower today than it was in the sixteenth century.

B. The two mining expeditions funded by Elizabeth I did not mine the same part of Kodlunarn Island.

C. The methods used to assess gold content of the soil samples provided by Frobisher were different from those generally used in the sixteenth century.

D. Frobisher did not have soil samples from any other Canadian island examined for gold content.

E. Gold was not added to the soil samples collected by Frobisher before the samples were examined.

我不明白为什么会选E.

我的思路是这样的:我对E取非,但并不使原结论不成立,故我认为不对。

若把not盖住,即:在Samples被测前,gold是被加到sample里去的,而不是sample里本身就含的,故,当年Frobisher检测到sample里金的含量高是假象,是错误的。这与结论:当年Frobisher的检测方法是错误的,是不谋而合,故对E取非后并未使原结论不成立,则E不应该是答案啊。

另外,本文提到了2个检测方法,一个是当年Frobisher用的检测方法,另一个是modern analysis采用的检测方法,不知道最后一句提到了the methods used to...是指哪一个方法呢?

请牛人不吝指点迷津,叩谢!
作者: tania_zhang    时间: 2010-8-31 21:20

若gold被加到了samples里之后才被 Frobisher测试的,Frobisher测出samples的含金量高的这个结论就是正确的了。但结论却认为Frobisher当时的结论是不正确的。但我们刚刚说了,Frobisher的测量结果是正确的(因为他所测的样本里却实含金量高),正好与原文的结论相反。故E选项是正确的。
楼主混淆了真实情况与F只是针对样本公布测量结果的相互关系。尽管若gold是后被加进样本中的,真实情况可能是本地的黄金很少。但Frobisher的测量结果仍然是正确的,即样本的黄金含量高,但Frobisher的测量结果并没说本地的黄金含量也会高。
作者: linglingdan    时间: 2010-9-1 20:52

F测的含量高 & 女王探险队没找到金矿 & 现代方法测出来的含量低  >>  F的方法不准确

做出这样argu的前提是 金子的含量没有变化,1可能金流失到现在导致含量低,2其他可能过去

的含量高。

选项里就e体现这一assumption。
作者: tingting520    时间: 2010-9-2 06:31

谢谢上面两位牛人,明白了
作者: wangliming    时间: 2010-9-8 06:43

为什么B不对呢?B说那两个开矿队没有在同一个地方开矿。如果取非就是那两个开矿队在那个地方把金子挖了,那么结论“F的方法不准确”就不成立了嘛。

请高人指点一下啊!
作者: xiruihuang    时间: 2010-9-8 20:32

我第一次的时候也是选B的,但是我觉得楼上的结论应该是推不出来的。有时候我们做题就犯了一个错误,自己推结论。相反选E已经很明白解释了。




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