题目内容：

I was giving a talk to a group of people.I____ the same talk to other groups before.

优质解答

填:had given
was giving 是过去动作,在此之前曾给其他几群人作过同样的报告,
故应用过去完成时.
句意:我当时正在给一群人作报告,在此之前我曾给其他几群人作过同样的报告