would have done,might have done,could have done,should have done分别表示什么意思?
问题描述：
would have done,might have done,could have done,should have done分别表示什么意思?
答
一、在虚拟语气中的用法1.should have done 表示“过去本应该做某事却未做.”其否定结构 shouldn't have done 表示 “过去本不该做某事却做了.”2.ought to have done 表示“过去本应该做某事却未做.”其否定结构 ou...