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

问题补充：

—You were brave enough to raise objection 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：由语境可知“我”“后悔”在会上提出异议，应接动名词。