Peter loos very upset.Anything wrong?He_____in the exam.It was very difficult
问题描述：
Peter loos very upset.Anything wrong?He_____in the exam.It was very difficult
A.should have failed B.must have failed C.should fail D.must fail
答
选B：must have done 表示对过去发生行为的推测,意思是“一定,准是”,只用于肯定句中.本题中,根据
.It was very difficult（考试很难）可知,他准是挂科了.
A选项,shoud have done 对过去应该做而没有做的行为的责备.本该...（实际上没做）如：You should have been here ten minutes ago.
你本应该10分钟之前来到这.（实际上没有）
C项 表示"义务,责任" 意思是“应该”
D项 不能表示对过去行为的推测