I can’t forget the day we join the party.A. thatB. whatC. whenD. how

问题补充：

I can’t forget the day we join the party.

A. that

B. what

C. when

D. how

答案：

A. that

B. what

(答案→)C. when

D. how

解析：先行词是the day指物, 且引导词在定语从句中做状语，只能用when，故选C