标题: PREP07 97 Industrialization and modern methods of insect control [打印本页] 作者: 123SherryGo 时间: 2016-11-6 11:07 标题: PREP07 97 Industrialization and modern methods of insect control Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.
A. while at the same time they have introduced some 100,000 dangerous chemical pollutants, having
B. while at the same time introducing some 100,000 dangerous chemical pollutants that have
C. while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have
D. but introducing some 100,000 dangerous chemical pollutants at the same time that have
E. but at the same time introducing some 100,000 dangerous chemical pollutants, having
这道题看到manhattan讨论了好多，但是自己还是不太懂。有如下两点疑问：
1.C为什么错
RON的意思是:C的which不对，解释如下
"which" can modify...
...a NOUN,
or
...a NOUN + preposition + other noun.
this version doesn't do either of these things. (it's NOT "noun + prep + noun", because "at the same time" is NOT a modifier of "pollutants".)
2. B为什么对
WHILE DOing按理说不应该是省略吗？
while running the marathon, james tripped and fell.
unreduced --> while he was running the marathon, james tripped and fell (past tense parallelism)
timmy has learned a lot of valuable lessons while employed with the company.
unreduced --> timmy has learned a lot of valuable lessons while he has been employed with the company. (present perfect parallelism)
然而这个题明显是while they have introduced怎么能省略成while introducing呢
作者: meiyw 时间: 2016-11-8 17:22
定于从句引导词which只能紧跟在名词或者（名词+介词+名词）短语后面，比如students of the school,at the same time是副词，不符合条件，就错了。这是gmat要求的。
第二个问题我不知道，只是上学时经常见这样的表达方式。作者: meiyw 时间: 2016-11-8 17:56
From the bark of the paper birch tree the Menomini crafted a canoe about twenty feet long and two feet wide, with small ribs and rails of cedar, which could carry four persons or eight hundred pounds of baggage
这句which跳过了修饰名词的两个介词短语修饰canoe，所以我理解at the same time主要问题是副词性。作者: 123SherryGo 时间: 2016-11-8 21:12
楼主说的那种往前看, 哪个前句的名词符合句意先行词就指代哪个的, 是that。
Which是就近原则, 最近的noun, 或者noun phase.
I. I always buy apples from Shandong, which are sweet and juicy. which在这里指apples from Shandong，成立.
II. Because there is a nice grocery store near my house, I always buy some apples on my way home, which are sweet and juicy. --apples on my way home 不能作为先行词，which在这里用法不成立。
此外, that 和which还有两个区别:
I. 前者为特指，后者为泛指.
II. that包含的信息对句意有决定性作用. which包含的信息即便忽略，对句意无甚影响.
此处的while是第二个，句意是想说这些methods有好的一面，然而也有其副作用. 因为有at the same time来强调两个正负作用的同时性, 所以从句补全确实是Industrialization and modern methods of insect control have improved the standard of living around the globe while they were introducing...