Simon is very regretful. If he had been more careful, he such a big mistake.
A. hasn’t made
B. hadn’t made
C. won’t have made
D. wouldn’t have made
网友回答
A. hasn’t made
B. hadn’t made
C. won’t have made
(答案→)D. wouldn’t have made
解析：句意:西蒙是很后悔的，如果他再仔细点，他就不会犯这么大的一个错误。这里是虚拟语气，根据had been可以看出是对过去的虚拟，故主句用would have done的形式，根据句意故选D。