题目内容：

I regret ____ harder at school.A.not to have worked B.not having worked
A为什么不对?

优质解答

regret （not）doing sth后悔(没)做过某事,所以用这个.
regret to do sth后接不定式时无否定式因为这个不定式的动词都表示说的意思.全句是很遗憾地去说,如 I regret to tell you that you didn't pass the exam.