Gmatprep上一道，怎么看正确答案就象错的

greattaste

Some patients who do not respond to therapies for depression may simply have received inadequacy treatment, having, for example, been prescribed a drug at dosage too low to be effective or having been taken off a drug too soon.

 正确答案是这样的，能否解释以下为什么对呢？

you5460

没错  having been 和 having been 通过or 平行

时态和前面分句一样

haitai

Nod

Jarod

分词在与句子主语一致的情况下作伴随状语很常见。