I wonder when they for Beijing. I will go to the train station to see them off when they

问题补充：

I wonder when they for Beijing. I will go to the train station to see them off when they .

A. will leave; leave

B. leave; will leave

C. will go; leave

D. go; leave

答案：

(答案→)A. will leave; leave

B. leave; will leave

C. will go; leave

D. go; leave

解析：句意：我想知道他们什么时候动身去北京，当他们离开的时候我想去火车站为他们送行。when为“当…时候”，主将从现：when为“何时”，从句用将来时。故选A。