---Have you found your book yet? ---No. I’m not sure where I it.A. leaveB. had leftC. coul

问题补充：

---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

答案：

A. leave

B. had left

(答案→)C. could have left

D. was to leave

解析：could have done “本能做某事实际没做”句意：你找到你的书了吗？没有。我不确定我能把它放哪？