[求助] 语法题目一道

Gavin_win

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 to be effective, or were

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

答案：A。

记得XDF白大侠说过，having been done 这种分词结构是错的，要改成从句的。这里确实答案。不解？？

请指教！！谢谢！！

ecw127

我觉得应该选A.

用排除法的话，DE肯定不对，D两个动作时态不统一，E been 前面省略have有点莫名奇妙。C 一定不对，as 后面没主语, 至于B, have状态不对，have a drug prescription表状态跟题目对不起来，只有A 了。　你说的having been done绝对错我想应该发生在此结构修饰名词时，而非此结构做修饰动词。

Gavin_win

多谢楼上的MM深更半夜为我解答－－有道理， 接受！！