Unluckily, we missed the train. we early.
A. must have set out
B. had set out
C. should have set out
D. set out
网友回答
A. must have set out
B. had set out
(答案→)C. should have set out
D. set out
解析：考查情态动词+完成式的用法：句意：不巧的是，我们错过了火车，我们本应该早点出发的。从we missed the train可知我们没有早出发，所以用should have done过去本应该做却没有，must have done过去一定做了..，选C。