12. Impact craters caused by meteorites smashing into Earth have been found all around the globe, but they have been found in the greatest density in geologically stable regions. This relatively greater abundance of securely identified crater in geologically stable regions must be explained by the lower rates of destructive geophysical processes in those regions.
The conclusion is properly drawn if which one of the following is assumed?
(A) A meteorite that strikes exactly the same spot as an earlier meteorite will obliterate all traces of the earlier impact.
(B) Rates of destructive geophysical processes within any given region vary markedly throughout geological time.
(C) The rate at which the Earth is struck by meteorites has greatly increased in geologically recent times.
(D) Actual meteorite impacts have been scattered fairly evenly over the Earth's surface in the course of Earth's geological history. (b)
(E) The Earth's geologically stable regions have been studied more intensively by geologists than have its less stable regions.
我选了d, why not correct?
正确答案是D啊。
可是为什么B错呢？请帮忙解释。谢谢。
题目说：A.陨石坑在地壳活动比较少的地方比较集中＝>B.得出是由于较少的地壳活动使得地表更好的保存了陨石坑。
但是A、B之间有gap：陨石坑在地面的分布原本是否是均匀的？是地壳活动破坏了一些陨石坑？
D弥补了论点：陨石坑的分布是均匀的。所以，题目得到支持。
不知道这样解释是不是清楚。。。。。。
非常清楚,juicemm的答案非常好,支持一下
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