— When did the couple die?— It was on May 12the earthquake hit WenChuan County.A. that B.

问题补充：

— When did the couple die?

— It was on May 12the earthquake hit WenChuan County.

A. that

B. which

C. when

D. what

答案：

A. that

B. which

(答案→)C. when

D. what

解析：考查定语从句和强调句型。本题定语从句的先行词是May 12, 定语从句的结构很完整，使用关系副词when.实际上在第二句中的最后还省略了that the couple died. 强调的是时间状语on May 12on the earthquake hit WenChuan County.句意：—那对夫妻是什么时候去世的？—就在在5.12汶川地震的时候，他们去世的。故C正确。