It was a meeting importance I did not realize at that time.A. thatB. whichC. itsD. whose

问题补充：

It was a meeting importance I did not realize at that time.

A. that

B. which

C. its

D. whose

答案：

A. that

B. which

C. its

(答案→)D. whose

解析：考查定语从句：先行词是a meeting，定语从句中缺少定语，用whose修饰importance，句意：这是一个那时我还没有意识到重要性的会议。选D。