求having done的用法！！两道新旧prep 题让我困惑

sdnmay

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对

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,

这是新prep1-188  答案是A



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错(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

这是老prep1-97 答案是B



having done正确的和错误的用法究竟是什么？求G友们的指点

sdnmay

RT      大家来总结一下having done的用法吧~~~~

lucky_fs

绝非NN，说下看法。

首先，having结构的错误用法是作为定语使用，当having做定语时要改为定从that have……； 而having结构作为状语使用时是可以接受的。

再看这两道题，having都是作为状语，所以单单在having上97题没有出错。97的考点不在having，而在they（they在同一句话中的指代对象要一致，A的they造成了与未划线部分they指代不一致的歧义）

不知道能不能帮助到mm一点点  也期待NN们来解答^ ^

sayysong

prep1-188
having amessed ... 现在分词的完成式做伴随，表示动作发生在draw之前。

同意楼上的“首先，having结构的错误用法是作为定语使用，当having做定语时要改为定从that have……； 而having结构作为状语使用时是可以接受的。”

prep1-97
while at the same time指明了从句的动作与主句的动作的同时性，所以不能用完成式，所以含有have introduced的A错。同时，也同意楼上的美女lucky_fs所说的they的指代混乱的歧义说。

sdnmay

恩恩~~~~谢谢楼上两位G友的指点~~~~

97题为什么排除A我的意见和你们一致  单独考虑having done的用法的话
老prep在解释97题时说“having在这里既可能做定语又可能做状语，有歧义“  按照这个说法188题having对好像是因为不管做定语还是做状语都是修饰同一个对象所以对？？这么理解对吗？

弱弱的问一下 having done为什么不能做定语啊？一见到having done确实是做定语成分就直接排除吗?
另外还有一个having been done  老prep里说”过去完成时的分词结构在GMAT中是一种错误的结构“   这个词是一出现就排除还是和having done 一样不能做定语修饰语？？

求大家指点~~

lorrain_cc

恩,有时态感存在要做定语必须是改成从句,因为分词不强调时态,强调的是多次,重复性.

wshsrt

having gone unregulated 修饰 chemical pollutant的      此举修饰成 前句了

洛洛洛洛

老PREP的那题having逻辑主语不对
关于新prep这个我用排除法做...但是楼上上上的一说，我现在了了～
原来可以做状语

waterlemonseed

外国网站上找到的，我觉得很有道理


Perfect Participle:

The perfect participle indicates completed action. You form the perfect participle by putting the present participle having in front of the past participle.

For example:-

Having done, having finished, having read, having spoken

It can be used to form the passive voice.

For example:-

Having improved her English Pia's promotion prospects were much better.

Option E indicates that "having kept" is a completed action. So, it is not correct.

旺雅晴子

D和E选项为什么不对呢？
可以把最后一个逗号后面的现在分词形式：now drawing solid conclusions about .....看成结果状语呀？？整句话的意思就是：神经学家掌握了20年的知识，(使得）现在得出某某结论。
求高人指点！