OG737 关于句子平行。修饰语问题

herb.yuan

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,

想请问一下，A为什么不对，主要是不明白“扩折号”在这里有什么作用，因为在曼哈顿语法书里说扩折号可以当作逗号，冒号，分号，所以在这里如果用作冒号，或者分号，后面不就应该是从新一个句子了吗，所以为什么还要有that的平行？另外 reducing 这里为什么表达不清楚？

herb.yuan

krystalchenkkk 发表于 2017-10-21 13:47
把这句话拎出来
our ancestors suffered an event, greatly reducing their numbers

喔喔喔懂了！多谢！

krystalchenkkk

herb.yuan 发表于 2017-10-21 10:00
嗯？我没懂诶，reducing 的逻辑主语不应该是an event吗？ 这个事件减少了他们的人数。？真的谢谢你啊，回 ...

把这句话拎出来
our ancestors suffered an event, greatly reducing their numbers

你看主语是不是ancestors，an event是宾语~

herb.yuan

krystalchenkkk 发表于 2017-10-20 23:24
A最大的问题在于reducing的逻辑主语是ancestors。
我个人觉得有没有that都问题不大，因为破折号的用法比较 ...

嗯？我没懂诶，reducing 的逻辑主语不应该是an event吗？ 这个事件减少了他们的人数。？真的谢谢你啊，回答了我这么多问题。

krystalchenkkk

A最大的问题在于reducing的逻辑主语是ancestors。
我个人觉得有没有that都问题不大，因为破折号的用法比较多。