—You were brave enough to raise objections at the meeting.--Well now I regret that.A. to

问题补充：

—You were brave enough to raise objections at the meeting.

--Well , now I regret that.

A. to do

B. to be doing

C. to have done

D. having done

答案：

A. to do

B. to be doing

C. to have done

(答案→)D. having done

解析：

此题考查regret的基本用法。常用的句型结构有：

regret ding sth/that:对某事感到懊悔,遗憾

regret to do sth.that为要做的事抱歉,遗憾

regret to have done将来完成时

regret having done:为做过的事感到后悔，抱歉综上所述，故正确答案选择D.