OG12-SC-21 C选项的解释！！哪位大神再帮我解释下！！

三岁半

OG12-SC-21
21 Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.
(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,
答案选A我是懂的，其他几个选项为什么错我也懂，除了C。
其实要是不看OG的解释C我也排除了，但是看了解释我就不懂了···
解释是这样的：Amassing, like having amassed, functions as an adjective, not a verb; the sentence therefore lacks the first main verb implied by the compound verb construction and are now drawing...
首先，我觉得having amassed不是做形容词，而是分词做伴随，解释说明neuroscientists的，是说neuroscientists在过去的20年已经做了····
同样，amassing我觉得也是分词修饰neuroscientists， 现在分词是表示主动的现在的一种持续性动作，而后面时间状语是over the twenty years, 应该用完成时，所以amassing不对。而且amassing直接修饰主语，中间没有逗号隔开，此分句不是一个完整的句子，于后面and are···无法形成并列。
我主要不明白的就是amassing在这里为什么是形容词。哪位sama能帮我解释一下啊~~~万分感谢！！！

三岁半

自顶~！不要沉下去啊   我不懂啊不懂啊~~~

beingchuang

前面不是句子，后面怎么用and链接呢？

namelessboy

OG12-SC-21
21 Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.
(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,
答案选A我是懂的，其他几个选项为什么错我也懂，除了C。
其实要是不看OG的解释C我也排除了，但是看了解释我就不懂了···
解释是这样的：Amassing, like having amassed, functions as an adjective, not a verb; the sentence therefore lacks the first main verb implied by the compound verb construction and are now drawing...
首先，我觉得having amassed不是做形容词，而是分词做伴随，解释说明neuroscientists的，是说neuroscientists在过去的20年已经做了····
同样，amassing我觉得也是分词修饰neuroscientists， 现在分词是表示主动的现在的一种持续性动作，而后面时间状语是over the twenty years, 应该用完成时，所以amassing不对。而且amassing直接修饰主语，中间没有逗号隔开，此分句不是一个完整的句子，于后面and are···无法形成并列。
我主要不明白的就是amassing在这里为什么是形容词。哪位sama能帮我解释一下啊~~~万分感谢！！！

-- by 会员 三岁半 (2011/8/18 13:04:20)

C 中 amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years 是现在分词短语修饰neuroscientists， 后面跟着and are, and 前后是应该是完整的句子（包含主谓宾），而现在分词短语不是一个完整的句子。and前后不平行，所以C错。
如果去掉and 这句就变成 Neuroscientists （amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years）修饰成分 are 也是正确的。

三岁半

介样呀~~  我也知道现在它是由现在分词修饰不是一个完整的句子，不能与and后面并列。
我主要纠结这个amassing是做形容词功能介个问题。
不过经你一说，貌似懂了~  就是说amassing引导的现在分词短语整个是做一个形容词的作用来修饰neuroscientists的，对吧？~

清飞扬

http://forum.chasedream.com/GMAT_SC/thread-583291-1-1.html#15267412

搜索下以前的帖子吧，其实基本所有的题目都是有过讨论的

三岁半

好的~~谢啦~！