I don’t know yesterday.A. when he will leaveB. when will he leaveC. when he leftD. when

问题补充：

I don’t know yesterday.

A. when he will leave

B. when will he leave

C. when he left

D. when did he leave

答案：

A. when he will leave

B. when will he leave

(答案→)C. when he left

D. when did he leave

解析：句意:我不知道他昨天什么时候离开的。本题考查的是宾语从句。从句中应该用陈述语序，故我们可以排除B和D；而且句子中有时间状语yesterday 昨天，故从句中应该用一般过去时，A是一般将来时，故选C。