PREP题 关于现在完成时having能否作修饰成分？

caopp

154.       (33193-!-item-!-188;#058&006626)

 

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   为什么这里先在完成时可以做修饰成分？

overthere33

分词做原因状语很常见的 完成时表示发生在主句时间之前

[此贴子已经被作者于2009/9/1 11:57:02编辑过]

caopp

分词作状语是很常见， 但是经常我们说现在完成时态不能做修饰成分， 我就想知道为什么这里可以。

比如：i knew the truth already having been revealed.   这句话是错的，因为现在完成时态不能做修饰成分。

[此贴子已经被作者于2009/9/2 1:26:43编辑过]

overthere33

以下是引用caopp在2009/9/2 1:22:00的发言：

分词作状语是很常见， 但是经常我们说现在完成时态不能做修饰成分， 我就想知道为什么这里可以。

比如：i knew the truth already having been revealed.   这句话是错的，因为现在完成时态不能做修饰成分。

你这是状语么？