Could you tell me when the train _______?A.leaves B.would leave C.has left D.had left

问题描述:

Could you tell me when the train _______?A.leaves B.would leave C.has left D.had left
请具体说明理由。

A为什么不选B?不对,这里不是过去式。Could在此只是表示用婉转的语气在问