ought to have done和should have done都是虚拟语气,只是前者

ought to have done和should have done都是虚拟语气,只是前者 should ought to have done 虚拟语气 should have done 与 could have done should have done 可以换成 ought to have done嘛? Ought to have done .must have done.should have done的区别 关于英语ought to have done 与should have done的区别 有need have done 英语：should have done是否用于虚拟语气? 虚拟语气中would could should might have done与had done都是表示过去,在用法上有 虚拟语气中的would/conld/should do/have done 与 did/had done有何区别 虚拟语气would have done 的用法 关于could have done 的虚拟语气 could have done和should have done