被动语态是英语中的一种语态，用来表示句子的主语是动作的承受者，而非执行者。在被动语态中，谓语动词由be动词加上过去分词构成。下面详细介绍被动语态的构成和用法：

一般现在时被动语态

构成：am/is/are + 过去分词

例句：The cake is made by my mother.

一般过去时被动语态

构成：was/were + 过去分词

例句：The letter was sent yesterday.

现在进行时被动语态

构成：am/is/are being + 过去分词

例句：The house is being painted by the workers.

过去进行时被动语态

构成：was/were being + 过去分词

例句：The book was being read by the boy when his father came in.

现在完成时被动语态

构成：has/have been + 过去分词

例句：The work has been finished by the team.

一般将来时被动语态

构成：will/shall be + 过去分词

例句：A new school will be built in our town next year.

被动语态的用法：

不知道或没有必要指出动作的执行者时

例句：The bridge was built last year.

当更加强调动作的承受者时

例句：The room hasn't been cleaned yet.

当动作的执行者不是人时

例句：The window was blown by the wind.

被动语态的基本结构是“be + 过去分词”，其中be动词根据时态、人称和数的变化而变化。有时by短语可以省略，尤其在不知道或不需要指出动作执行者的情况下。

希望这些信息对你有所帮助。