---Did they have a good time at the party?
---Judging by their smiles, they have enjoyed themselves.
A. might
B. must
C. could
D. would
网友回答
A. might
(答案→)B. must
C. could
D. would
解析：考查情态动词用法。Might have done 也许做了某事；must have done一定做了某事；could have done本可以做却未做；would have done会做某事；句意：—在聚会上你玩的开心吗？—从他们的微笑来看，他们一定完的很开心。