--- Could you tell me ?
--- Certainly. In half an hour.
A. when will the train to Chengdu leave
B. when the train to Chengdu left
C. when would the train to Chengdu leave
D. when the train to Chengdu will leave
网友回答
A. when will the train to Chengdu leave
B. when the train to Chengdu left
C. when would the train to Chengdu leave
(答案→)D. when the train to Chengdu will leave
解析：英语宾语从句中一般为陈述语序。根据下文，当然了，半个小时后。可知上文描述的是将来的动作，故用一般将来时态，选项A为倒装语序，故选D。