—You were brave enough to raise objections at the meeting.
— Well, now I regret ________ that.
正确答案： D
本题解析：
regret 后所跟动词有 to do 与 doing 两种形式，不定式表示“为做某事而遗憾”， doing 表示“为做过某事而后悔”。“ having done ”则更强调动作已发生而无法挽回。
The wounded soldiers would recover quickly if they were well ________.
_______ at all is worth doing well.