I can’t find Xiao Ping. Where did you see him this morning?In the reading room he

问题补充：

--- I can’t find Xiao Ping. Where did you see him this morning?

--- In the reading room he often studies in.

A. that

B. where

C. in which

D. the one

答案：

(答案→)A. that

B. where

C. in which

D. the one

解析：考查定语从句，先行词是the reading room，定语从句中in缺少宾语用关系代词that，句意是：--我找不到小平，今天早上你在什么地方看见他的？--在他经常看书的图书馆。选A。