单选题 I was giving a talk to a large group of people, the same talk I ______ to half a dozen other groups.

【正确答案】 C
【答案解析】[考点] 时态
[解析] “我正在做报告”用的是过去时，而“我给另外6组人做报告”发生在这一事件前，故应用过去完成时。