语法题目 谢谢大家了！！！

waytouing

这是综合og13 语法部分的25题 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：A 比较疑惑的地方在于：题目中的its 指代的不应该是 a wealth of knowledge 吗？？那这样来说的话， 原句是不对的呀， 就应该将原句改为由 a wealth of knowledge 做its的主语呀。我自己的答案选的是e。 不知道e为什么错了？og上的解释也看了 但是解决不了我的问题呀~~还有一个问题 ，就是have 什么时候要加-ing 呢, 这里的having amassed 这样的形式结构表明了什么意思呢？？跟have amassed 有什么区别呀？？？还请各位牛牛们帮忙看一下~~~·！！万分感谢呀！！！！

xuyuanwai

its指代的是brain，and后的意思是“大脑从幼时到。。。的发展”，having amassed分词结构修饰neuroscientists，are是谓语。句子结构其
实很简单就是N,having amassed...，are..E中的have amassed直接成谓语了，now drawing a conclusion变成了伴随。这句话是讲科学家们积累了这么多知识，终于得出了结论，所以句子重心应该放在得出结论上，将have amassed作为谓语（句子核心）是本末倒置了。且drawing conclusion的伴随容易引起修饰歧义，可能是修饰adulthood。：)

waytouing

嗯嗯 终于明白了 太谢谢啦！

sabineceng

纠正楼上关于having amassed的观点，这里having amassed 不能作定语修饰Neuroscientists，having done结构不可作定语，不能修饰名词。而是作状语修饰整个主句。

waytouing

那having done 这个结构表示的是什么意思呢？为什么这里的have要以ing 的形式出现呢？

sabineceng

having done 是have done的分词形式，这里have amassed不能用动词

形式来作状语，所以必须用分词形式来作状语来修饰句子。

sisleycheerup

可以找个老美GMAT tutor问问
Verbal部分很强