OG13 66 有疑问！！

doudoucc

In a plan to stop the erosion of East Coast beaches, the Army Corps of Engineers proposed building parallel to shore a breakwater of rocks that would rise six feet above the waterline and act as a buffer, so that it absorbs the energy of crashing waves and protecting the beaches.
(A) act as a buffer, so that it absorbs
(B) act like a buffer so as to absorb
(C) act as a buffer, absorbing
(D) acting as a buffer, absorbing
(E) acting like a buffer, absorb

这道题目选的是C. 这个从平行结构上去理解没有问题，但是我的疑问就是分词的逻辑主语不应该是主句的主语吗？那么aboring 和 protecting 的主语就应该是 Army Corps 。这个好像有点不符逻辑，那么是不是这里的分词结构有什么特殊的用法呢？请各位NN指教啊！

sayyessi

In a plan to stop the erosion of East Coast beaches, the Army Corps of Engineers proposed building parallel to shore a breakwater of rocks that would rise six feet above the waterline and act as a buffer, absorbing the energy of crashing waves and protecting the beaches.

这里的句子结构为：the ACE proposed building parallel to shore a breakwater..., absorbing ...and protecting....

其中absorbing与protecting在这里面作伴随结果状语，逻辑主语为前面整个句子（the ACE proposed building parallel to shore...)。

doudoucc

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,
这道题目里的A是错的，但我想不明白这里的现在分词不能做结果状语吗？