It was at the school gate I met an old friend of mine after class.A. thatB. whichC. where

问题补充：

It was at the school gate I met an old friend of mine after class.

A. that

B. which

C. where

D. why

答案：

(答案→)A. that

B. which

C. where

D. why

解析：当指代整句话时，四个选项中引导词只能用that，故选A，下课后是在学校门口，我遇到了一个老朋友。