— Robert is indeed a wise man.
— Oh, yes. How often I have regretted his advice!
A. to take
B. taking
C. not to take
D. not taking
网友回答
A. to take
B. taking
C. not to take
(答案→)D. not taking
解析：表示对所发生的情况表示遗憾或后悔，动词regret后习惯上要用动名词，不用不定式，因此可排除A和C。再根据句意，此处的动名词应用否定式，故选D不选B。