----I missed the first part of the film. It was really a pity．
----You home half an hour earlier.
A. should have left
B. must have left
C. should leave
D. must leave
网友回答
(答案→)A. should have left
B. must have left
C. should leave
D. must leave
解析：句意：--- 我没看到电影的开头，真是可惜啊。--- 你本应该早半小时从家里出发。should have done 表示“过去本应该做某事却未做。”must have left表示一定离开了。表示对过去的推测，C和D都是对现在的推测，排除。故选A。