must have done是虚拟语气的一种吧?

must have done是虚拟语气的一种吧? must have donemust have done 的用法详细说明.可以归结为虚拟语气里面的么?must have been down 是must have down 的被动语态么 虚拟语气中对过去的虚拟主句否定是用would have not done or would not have done? 情态动词+have done是虚拟语气吗? shouldn’t have done是虚拟语气么? She must have gone out early,for she had not shown up at breakfast.这个句子为什么用“must have gone”,整个句子是虚拟语气吗?虚拟语气中不是用could(should would might)+have done的形式吗?在这里为什么用must,另外翻 would/could/must have done在虚拟语气中怎么用? 虚拟:should have done ,could have done请教虚拟语气的几种情况是在什么时候使用的:should have done 2.could have done 3.would have done(是虚拟吗?) 4.might have done(是虚拟的用法吗?) 比如:Mary couldn't have recei should/must/would/could/might/may have done的问题!这些词组里到底哪些是表示推测.哪些是虚拟语气啊?晕了.还有就是could和can什么关系（区别）?might和may什么关系? 请问must的否定形式是不是不能表推测?有木有mustn't have done 滴形式?推测和虚拟是推测和虚拟到底是什神马?must have done 可以表推测,能表虚拟吗?偶乱了. 虚拟语气倒装疑问句应该怎样书写呢?had sb done sth,would sb have done sth.这种句式可以算作带有虚拟语气倒装的疑问句嘛（对过去虚拟?）我的意思是正常的虚拟语气句子不是if sb had done sth,sb would h 关于would rather的虚拟语气would rather have done跟would rather had done是不是都是表示对过去的虚拟语气? 情态动词+have done什么时候用 是只用于虚拟语气里吗 That latest car must have cost you a pretty penny.Oh ,no,---- it ,didn`t.是不是虚拟语气的否定回答呢,must have done,要一一的去掉后剩下过去式cost ,所以要用过去式?、 would have done非虚拟语气情况下的用法和意义 He _have shown you around himself but he was busy then.选项：might /must must 为什么?我翻了下语法书 might have done 有表示虚拟语气 本来可以却没有,must have done 貌似没有表示虚拟 只表示肯定的推测 虚拟语气 ifif引导的虚拟语气,从句时态倒退一步吗?主句呢?在对过去进行虚拟时,是不是 if sb had done sth ,sb should have done sth?对现在的虚拟,是不是 if sb did sth,sb should do sth 对将来的虚拟是怎样的? 情态动词+ have done一定用于虚拟语气吗