What were you trying to prove to the police ?-- I was last night.A. What .B. Where .C.

问题补充：

What were you trying to prove to the police ?

---- I was last night.

A. What .

B. Where .

C. That

D. When.

答案：

A. What .

(答案→)B. Where .

C. That

D. When.

解析：考查省略句，该句为省略句式，完整的是I was trying to prove to the police where I was last night.