Is this school you used to study?A. whereB. at whichC. the oneD. that

问题补充：

Is this school you used to study?

A. where

B. at which

C. the one

D. that

答案：

(答案→)A. where

B. at which

C. the one

D. that

解析：句意：这个学校是你过去学习的地方吗？this school是主语，where引导的是表语从句，它在从句中作状语，其他的连词都不能作表语从句中作状语，故选A。