求教OG13语法题97

Jianke311

Some anthropologists believe that the genetic homogeneity evident in the world’s people is the result of a “population bottleneck”-at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.

A. at some time in the past our ancestors suffered an event, greatly reducing their numbers
B.that at some time in the past our ancestors suffered an event that greatly reduced their numbers
C.that some time in the past our ancestors suffered an event so that their numbers were greatly reduced,
D. some time in the past our ancestors suffered an event from which their numbers were greatly reduced
E.some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,

没看懂这句的意思,前面既然说是基因一致"genetic homogeneity evident ",后面怎么又出现基因变化"genetic variation"呢?求高手赐教. 答案是B

kiwifoodtown

这就是题目里所说的“population bottleneck”的结果，人类祖先经过自然选择，种群数量减少了，但由于适应了环境，导致基因的多样化，所以说在世界的不同人种的基因是同种类的。

另：GMAT SC不考察科学知识，而是考的语法能力，没必要搞懂这些知识，我们要关心的是它们这些句子的对错。

Jianke311

不好意思啊，还是不明白，因为“thus"表示的是结果吧，种群数量减少了，为什么基因多样化了呢?难道意思是人类基因多样化从而适应环境？ 那和前半句还是没多大关系啊？
我是感觉改错很多都需要逻辑推理的,所以弄懂意思挺重要. 不过还是感谢解答。

Maximus07

适应了不同的环境当然基因会多样化啊。。。中学的生物知识啊。。。

cxroger

楼主，理解错了，不是导致基因多样化，是减少了基因的多样化。
that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation.

“that greatly reduced their numbers and thus our genetic variation”.
人口减少，使得基因多样化减少。

Jianke311

还是有点糊涂了,thus可以这样用么？

兰心寒

Jianke311 发表于 2012-11-6 00:30
还是有点糊涂了,thus可以这样用么？

Ron大神说过，不要去质疑OG里SC做答案的句子的正确性。
thus有种用法是in this way/in this manner，像这样，以这种方式....
我觉得这里应该是这种解释