求NN帮忙啊og13 97题

xxy931211

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,
The underlined part of this sentence is an explanatory rewording of the clause that follows believe. Scientists believe that X—[in other words,] that Y. In this construction, X and Y are parallel clauses.

A. The omission of that after the dash makes the function of the final clause unclear. The structure makes that clause appear to be an awkward and rhetorically puzzling separate assertion that the writer has appended to the prior claim about what the anthropologists believe. The agent or cause of reducing is unclear.
B. Correct. Repetition of that effectively signals the paraphrasing of the belief.
C .The preposition at before some time is missing; without at the adverb sometime would be needed instead of this two-word noun phrase. The modifier of event is expressed with a wordy passive construction, which destroys the parallelism between it and what follows.
D .Repetition of that signals the paraphrasing of the belief and is therefore needed. The preposition at before some time is missing. The modifier of event is expressed with a wordy passive construction, which destroys the parallelism between it and what follows.
E .That is repeated in the paraphrase, but in the wrong place. A possible, and absurd, reading of this version is that our ancestors suffered an event in order to willfully reduce their own numbers and thus our genetic variation.

请教下破折号后面的是什么成分呢？

believe that X—[in other words,] that Y 这个是固定结构吗？Y前一定要加that吗为什么？
A的解释中说The agent or cause of reducing is unclear ，但我为什么觉得cause很明确呢，就是suffer an event呀
求大神翻一下解释好吗，看不懂啊

风吹枫铃

不客气啊，大家都是在学习中，加油加油！

xxy931211

风吹枫铃 发表于 2013-10-30 13:49
A. SVO, doing. 这种句子，doing必须修饰S（主句主语），做S的伴随状语，或者doing修饰SVO整个句子，做结果 ...

万分感谢大神啊

风吹枫铃

A. SVO, doing. 这种句子，doing必须修饰S（主句主语），做S的伴随状语，或者doing修饰SVO整个句子，做结果状语。doing永远不会修饰O。本题中就是reducing可以指一句话也可以指ancestors，但是指ancestors就错了，所以reducing指代有问题

B. 正确

C. some time 前面没有at, some time 就从介宾结构（不是句子主要成分，即不是SVO中任何一个）变成了名词，但是我们现在不需要名词，想要对必须改成sometime（副词）

D. some time问题同c；
另外，D最后用了被动语态，their numbers were greatly reduced and thus our genetic variation, and前后一个是句子一个是词组，不平行

E. so as to 表示目的，ancestor不能故意suffer然后目的是reduce number的。。

补充so 和such
(1）so as to/ so that 表目的
（2）So+形容词+as to.../ so+形容词+that 表示结果
（3）such+n.+that 表示结果
（4）such that 一定错！