He the test, but he wasn’t careful enough.
A. was able to pass
B. must have passed
C. could have passed
D. might be able to pass
网友回答
A. was able to pass
B. must have passed
(答案→)C. could have passed
D. might be able to pass
解析：考查虚拟语气。句意：他本来能够通过考试，但是他不够细心。“would+have+done”表示对过去事情的假设，表示本来会做而没有做的动作。联系句子意思可知选C。