问题补充:
I regret hard at school, or I would have succeeded in passing the exam.
A. not to work
B. having not worked
C. to have not worked
D. not having worked
答案:
A. not to work
B. having not worked
C. to have not worked
(答案→)D. not having worked
解析:regret doing sth.后悔做过某事;regret to do sth.遗憾(抱歉)地要做…