The criminal _______ murdering the judge, unfortunately, an unexpected accident made him lose his consciousness.
A．might have admitted B．could have admitted
C．should have admitted D．must have admitted
B
【解析】
【分析】
【详解】
考查情态动词+have done结构。句意：罪犯本可以承认谋杀了法官，但不幸的是，一场意外事故使他失去了知觉。A. might have admitted可能已经,可能性很小；B. could have admitted本来能做成的（却没做成）；C. should have admitted本应当做某事；D. must have admitted必定做了……（表示对过去的推测）。结合后文unfortunately, an unexpected accident made him lose his consciousness.可知此处表示罪犯“本可以承认谋杀法官，却没做成”，应用could have done。故选B。