be动词的过去式过去分词是啥（被动语态助动词be ）

英语中被动语态由“助动词be 动词的过去分词”构成。助动词be有时态、人称和数的变化。被动语态后的by短语有时可省去。

(1) 被动语态的用法：

① 不知道谁是动作的执行者(即不知道谁做)时用被动语态,省略by短语。如：A man was killed in the accident.(一个人死于事故)/ This window was broken yesterday.(这扇窗子是昨天被打破的)

②不说或者众所周知是谁做时,用被动语态,省略by短语。如：Rice is also grown in this place.(这个地方也种水稻)/ A railroad will be built here in three years.(三年之后这里将要修建一条铁路)

③强调动作的承受者,句尾加by短语。如：It was written by Lu Xun.(它(书)是鲁迅写的)/ A pet dog is never killed by its owner.(宠物狗是不会被主人宰杀的)