--- 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：考查单词regret，regret doing sth意思“后悔做过某事”，其否定形式regret not doing sth；regret to do sth意思“后悔做某事”，句子意思“我后悔没有听取他的建议”，所以选D