Simon is very regretful. If he had been more careful he such a big mistake.A. hasn’t mad

问题补充：

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

答案：

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。