完成形式：I regret not having taken your advice.

被动形式：This question is far from being settled.

4、句首为主，谓为单，否定直接加在前

动名词作主语时，位于动词一律用单数，:
Talking mends no holes.

动名词的前面直接加上否定词就可以表达否定概念，如：
I am sorry for not returning you the book in time.