被动句的结构是主谓结构.the workers build a house.主语 the workers 谓语 build 宾语 a houseA house is built (by the workers).主语 a house 谓语 is built (补语 by the workers)被动语态中,谓语的结构就是 be done,这与主系表没关系.供参考.
