---Where did you come across our Chinese teacher ?- It was in the supermarket I purchas

问题补充：

---Where did you come across our Chinese teacher ?

--- It was in the supermarket I purchased mooncakes．

A. that

B. which

C. where

D. when

答案：

A. that

B. which

(答案→)C. where

D. when

解析：考查定语从句：句意：--你是在哪儿遇到我们的语文老师的？--是在我买月饼的超市。说明是定语从句，先行词是the supermarket，定语从句缺少的是地点状语，用where引导定语从句。选C。