—Mr. Wang is in Nanjing for a trip.
—Oh, really? When he the trip?
A. does; start
B. will; start
C. did; start
D. is; starting
网友回答
A. does; start
B. will; start
(答案→)C. did; start
D. is; starting
解析：根据语境可知此句的含义是什么时候开始旅行的？描述的过去事情，故用一般过去时。因有when引导，故是特殊疑问句，其基本构成是特殊疑问词+一般疑问句？