— Where did you meet your middle school teacher?— It was in the supermarket I was doing

问题补充：

— Where did you meet your middle school teacher?

— It was in the supermarket I was doing some shopping with my son.

A. that

B. where

C. when

D. which

答案：

A. that

(答案→)B. where

C. when

D. which

解析：考查固定句型。句义：你在哪儿遇见了你的中学老师呢？在我和我儿子一起买东西的超市里。把握关键词It was…，首先考虑到强调句型：it was …+ that…,然后把it was和that 去掉，看句意是否完整，本题完全正确，排除A C D ,所以B正确。