请教一道语法题

luyinan

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.

划线部分为什么是对的？having been done这个结构能这么用吗？ 谢谢

laipiyu

能,现在分词分词短语句尾做状语

luyinan

谢谢