问题补充:
By the time he arrived in Beijing, we there for two days.
A. will have stayed
B. stay
C. have been staying
D. had stayed
答案:
A. will have stayed
B. stay
C. have been staying
(答案→)D. had stayed
解析:考查时态。by the time用完成时态,根据arrive用过去时态,故用过去完成时,表动作先于发生。选D。