I know it’s normal for such a thing to happen, but we it if we’d been more careful.
A. need have avoided
B. could have avoided
C. will have avoided
D. had avoided
网友回答
A. need have avoided
(答案→)B. could have avoided
C. will have avoided
D. had avoided
解析：考查虚拟语气：句意：我知道这样的事情发生是很正常的，但是如果我们更小心点本来是可以避免的。根据从句if we’d been more careful.可知是和过去相反的虚拟语气，主句用could have done，need have done本来需要做…而没有做，will have done是将来完成时，had done是过去完成时，选B。