问题补充：
—Could you tell me ?
—Certainly. In half an hour.
A. when will the train to Beijing leave
B. when the train to Beijing would leave
C. when the train to Beijing left
D. when the train to Beijing leaves
答案：
A. when will the train to Beijing leave
B. when the train to Beijing would leave
C. when the train to Beijing left
(答案→)D. when the train to Beijing leaves
解析：本题考查的是特殊疑问句作宾语从句，要用陈述句语序。故选D
