两个句子的用法看不懂 求助！！！！！

chenariel21

OG13的25题 搜过CD的帖子，但没有答案。我的问题是这里的having amassed 是一个什么用法？ 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 阅读里的选项不太懂结构    civlians 不是名词吗 They maintained as civilians their enthusiastic allegiance to the armed forces.

闻鹿鸣

comma+ing 结构是修饰语，修饰前面的那个Neuroscientists，是说他们是已经在过去20年积累大量关于人脑如何如何的经验的

闻鹿鸣

They maintained their enthusiastic allegiance to the armed forces.这是主要的意思，as+名词，这里修饰they，当然你就当修饰语就好，阅读的时候可以忽略掉的内容（个人拙见，如有不同请勿拍砖）

chenariel21

upupupupup

chenariel21

闻鹿鸣 发表于 2015-9-21 11:54
comma+ing 结构是修饰语，修饰前面的那个Neuroscientists，是说他们是已经在过去20年积累大量关于人脑如何 ...

好像懂了 之前看到over the past 20 years 以为要用完成时态的

闻鹿鸣

chenariel21 发表于 2015-9-22 02:55
好像懂了 之前看到over the past 20 years 以为要用完成时态的

这个逗号加ing形式是不管时态的