He the exam, but he was too careless.
A. could have passed
B. couldn’t have passed
C. must have passed
D. may have passed
网友回答
(答案→)A. could have passed
B. couldn’t have passed
C. must have passed
D. may have passed
解析：此处could have passed the exam表示本能通过考试，实际上没有。句意：他本能通过考试的，但是他太粗心了。