请教一道gmat prep 题 思路 谢谢！

badboy2009

`kankan

lisy

以下是引用crazecat123在2007-10-4 12:40:00的发言：
I think the paragraph is basically saying that because of test case in the lab we can find out about more about the earth crust where fullerenes were formed.  The underlying assumption is that synthetic and naturally occurred fullerenes are similar in structure and property.  So weaken the conclusion, we have to say that synthetic and natural fullerenes are not the same thing.  A doesn't weaken the argument (if it doesn't say it, don't assume), and B does (it says previous unknown).

嗯哪，我是学化学的，对于合成化学物质，structure不一样反应条件可就天差地别，就像石墨和钻石，同样都是碳，但是大家都知道形成他们的条件不一样的，所以B weaker了假设。

而A，只是说陨石上也发现这种物质，和假设没有关系，如果地质学家连地层中发现的物质和陨石上来的都分不清楚，那就白干活了

crazecat123

I think the paragraph is basically saying that because of test case in the lab we can find out about more about the earth crust where fullerenes were formed.  The underlying assumption is that synthetic and naturally occurred fullerenes are similar in structure and property.  So weaken the conclusion, we have to say that synthetic and natural fullerenes are not the same thing.  A doesn't weaken the argument (if it doesn't say it, don't assume), and B does (it says previous unknown).

lisony

同问，我也不太明白

micerain

Although fullerenes-spherical molecules made entirely of carbon were first in the lab, they have since been found in nature, formed in fissures of the rare mineral shungife. Since lab synthsis of fullerenes requires distinctive conditions of temperature and preesure, this discovery should give geologists a test case for evaluating hypotheses about the state of the earth's crust at the time these naturally accurring fullerenes were formed.

问 weaken:

A Some fullerens have also been found on the remains of a small meteorite that collided with a spacecraft.

B The naturally occurring fullerenes are arranged in a previous unknown crystalline structure.

答案是B

但我对A有疑惑 如果这些东西有些来自meteorite, 即外来东西，如何能够测出地球的东西

相反B 即便它的结构你不知道，但是你已经从实验室提取过它，知道它所需要的温度，压强等，自然可以知道地球在构造它时所需要的条件