must have been,can not have been

must have been,can not have been

must have been后面可以加过去分词和现在分词。must have been done对过去的推测，被动形式，一定被……This village must have been hit by hurricane, for we saw the ruined houses and the fa实际上，情态动词+have done还可以用来表示对事物的推测。举个例子，新概念3第一课里面就有这样的句子：As on pumas had been reported missing from any zoo in the country, this o

must have been 中have 的秘密There must have been thousands of people.一些同学会认为must have been 是某种形式的完成时态，其实不是。must be 一定（对现在或将来事实肯定must have been的用法Must Have Been的用法Must have been是一个常用的英语短语，它表示对过去发生的事情的推测或猜测。这个短语通常用于表达对某个事件或情况的推测，而且通

must have been 美英na.必然；must = should 或would surely 英汉na. 1. 必然2. must = should 或would surely 3. 必须1. "Imusthavebeenawonderfulletter,AuntStephia是doing 或是done 不可以是do 因为must have been其实相等於was/were/-所以在主动语法时必须是-ing 而在被动语法时必须是-过去分词( done)不存在do的可能性

must have done：是说话者对过去情况的十分肯定推测。不是“过去完成时”（过去完成时的构成：had donemust have been和must be的区别在have。因为本句是指对过去情况的推测，所以必须要用“情态动词+动词的完成式”。ha