It was in the school he had studied he began the important experiment.A. that; whereB. i

问题补充：

It was in the school he had studied he began the important experiment.

A. that; where

B. in which; which

C. where; that

D. where; in which

答案：

A. that; where

B. in which; which

C. where; that

D. where; in which

解析：这是一个强调地点状语的强调句。