[求助] 关于having的问题

having作定语通常都是错的。那having可以作伴随状语吗？能不能看到主句后出现逗号+having……不管是作定语还是状语，就都是错的呢？谢谢~

Some patients who do not respond to therapies for depression may simply have received

inadequate treatment, having, for example, been prescribed a drug at a dosage too low to be

effective or having been taken off a drug too soon.

(A) having, for example, been prescribed a drug at a dosage too low to be effective or having been

(B) having, for example, a drug prescription that was ineffective because the dosage was too low,

or being

(C) as, for example, having too low of a dosage of a prescribed drug for it to be effective, or being

(D) when they have, for example, been prescribed too low a drug dosage for it to be effective, or

were

(E) for example, when they have a drug prescription with a dosage too low to be effective, or been

A.   正确。

188.      (26379-!-item-!-188;#058&001961)

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,

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, and

have

(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have

(E) but at the same time introduce some 100,000 dangerous chemical pollutants, having

答案：B

这题在Prep笔记里给的解释是“having gone…分词结构有作伴随状语修饰have introduced的

歧义，而不是作pollutants的定语。”

这个解释怎么理解呢？是不是看到 名词结尾，+ having done 就存在有作定语或者状语的歧义，就算错呢？

,+doing应该首选作为伴随状语来看待，而分词做后置定语一般是不加逗号的。

，+doing 也出现做后置定语的情况，这时，往往修饰主语且出现在句首，不容易造成歧义：

例如:

A person traveling, working or studying in a part of Nigeria can still communicate with other people in English.

，+doing比较麻烦的歧义可能在于，同时可以伴随主句谓语动词和从句中的主句谓语动词，

比如6L的例子，

having gone virtually unregulated since they were developed more than 50 years ago.

可能修饰主句have improved ，也可能修饰从句中的主句的谓语动词have introduced 。

造成歧义。

open to discuss.

再来一个例子

prep1-14