Question

I regret ________ hard at school, or I would have succeeded in passing the exam．

1. A.
   not to work
2. B.
   having not worked
3. C.
   to have not worked
4. D.
   not having worked

Answer 1

D
regret doing sth．后悔做过某事；regret to do sth．遗憾(抱歉)地要做……根据句意第一个空应该用动名词，这样排除了A、C项。动名词的否定形式是在动名词前面加not，故选择D项。