1.被动语态的基本时态变化:被动语态通常为十种时态的被动形式,各种时态的被动语态形式为:被动语态由be+过去分词构成,be随时态的变化而变化。 以do 为例 1) am/is/are +done 一般现在时 例:Visitors are requested not to touch the exhibits. 2) has /have been done ...