— Could you tell me            ? 

— Certainly. In half an hour. [ ]

A. when will the train to Chengdu leave

B. when would the train to Chengdu leave

C. when the train to Chengdu leaves

D. when the train to Chengdu left

不需要密封保存的药品是（　　）

A．氯化钠

B．氧化钙

C．氢氧化钠

D．浓盐酸