询问一道恐龙灭绝和行星撞地球(逻辑)题

yli161

原题是：Iridium, a hard, whitish metal similar to platinum, is extremely rare on Earth. Extremely high concentrations of iridium on Earth result
from only two scenarios: massive volcanic eruptions that release iridium from deep within the Earth and meteorites that shower down on Earth from space. When scientists found concentrations of iridium 30 times higher than normal in rock stratum from 65 million years
ago, they concluded that a massive meteor or comet hit the Earth and caused the massive extinction of the dinosaurs.

Which of the following, if true, most strongly supports the scientist’s conclusion?

A. Volcanoes massive enough to generate high concentrations of iridium are very rare.
B. Massive volcanic eruptions occurred frequently 80 million years ago.
C. Most scientists support the hypothesis that a cosmic impact wiped out the dinosaurs.
D. The massive extinction that occurred 70 million years ago killed not only the dinosaurs but also 70 percent of all life on Earth.
E. A comet struck the earth some 120 million years ago, but no widespread extinction occurred.


请问答案是什么？

peculiar615

本来选A的，结果老外的分析比较地道，还是B

红衫骁将

yli161 发表于 2012-10-8 00:33
Choice B strengthens the argument by showing that volcanic eruptions occurred frequently before the ...

解释完全正确。

lxtbkl

所以选B

lxtbkl

是说80million年前火山常爆发，可能产生了很多的Ir,但即使这样，文中表明65million年前的Ir的含量还是比普通岩层中高出30倍，所以说岩层中的Ir的过高不是由于火山爆发形成的，而只可能是撞击形成的。当然如果80million年前火山常爆发形成不了Ir,不用说65million年前的Ir的含量异常肯定是由于撞击形成，因为高浓度Ir的形成文中表明只有2种途径。

不如阿帕斯

我觉得如果按老外那么说，我们就还需要知道：80之前就有恐龙，它们经历80火山而不死。那不就违背ETS的不涉及专业知识？

才疏学浅，觉得选A

jasondang

这道题选A。通常逻辑题，我们只要能证明或者否定它的假设，我们就能加强或否定它的结论。这道题的前提条件是concentrations of iridium 30 times higher than normal in rock stratum from 65 million years ago，那么作者推出结论的假设就是，这种high concentration 的iridium不是由火山爆发而是由彗星撞地球得来的。那么，我们如果可以找到一个能够证明这个假设的选项，那么就可以加强作者的结论。显而易见，答案是A，因为只有这个选项极大削弱了high concentration的iridium是火山爆发得来的可能性。B选项的问题在于，它与我们结论的假设无关，也就是说它没有考虑到iridium concetration的问题，虽然从另一个角度也说的过去（尽管我觉得80million 和 65million年代差的也挺久的），但是没有从根本上支持到作者的假设，所以不是最佳选项。

novaleilei

表示一看就是选的B

Channery

A. Volcanoes massive enough to generate high concentrations of iridium are very rare.

是火山少，这个修饰语太长了，让人看成iridium少了，太具有欺骗性了！

bedrop

本来也觉得是a的
看了你的解释我觉得我被那个老外说服了。。。