请教一道gmat prep 题 思路 谢谢！

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