问题补充:
By the time you arrive in Liverpool, we in France for two weeks.
A. shall stay
B. have stayed
C. will have stayed
D. have been staying
答案:
A. shall stay
B. have stayed
(答案→)C. will have stayed
D. have been staying
解析:考察时态。句意:当你到达利物浦时,我们已经在法国两个星期了。可知下文描述的是在将来某个时间点前完成的动作,故用将来完成时态,选C。