It is most instructive lecture that I since I came to this school.A. attendedB. had atten

问题补充：

It is most instructive lecture that I since I came to this school.

A. attended

B. had attended

C. am attending

D. have attended

答案：

A. attended

B. had attended

C. am attending

(答案→)D. have attended

解析：从时间状语 since I came to this school可以看出要与现在完成时连用。故选D。句意，这是自从我来到这个学校以来听过的最有教育意义的讲座。