I was giving a talk to a large group of people, the same talk I _______ to half a dozen other g...

I was giving a talk to a large group of people, the same talk I _______ to half a dozen other g...

C

此题提供的语境是：我当时正在给一群人作报告，这个报告我曾给其他若干批人讲过。由于was giving为过去进行时，而“曾给其他若干批人讲过”显然发生在was giving这一过去时间之前，故用过去完成时，即答案选C。