--Have you found your book yet?
--- No, I’m not sure where I it?
A. leave
B. had left
C. could have left
D. was to leave.
网友回答
A. leave
B. had left
(答案→)C. could have left
D. was to leave.
解析：本题考查时态。根据句意：——你还没有找到你的书？没有，我不确定我能够把它丢哪儿了。故用could have done本能够做，选C。