由助动词be加过去分词构成,时态通过be表现出来,各时态结构如下表:
一般现在时被动:be(am,is,are)+done;
一般过去式被动:be(was,were)+done;
一般将来时被动:shall/will be+done;
过去将来时被动:should/would be+done;
现在进行时被动:be(am,is,are)being+done;
过去进行时被动:be(was,were)being+done;
现在完成时被动:have/has been done;
过去完成时被动:had been done