Question

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

Answer 1

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