被动语态的谓语动词的单复数与主语的单复数一致。例如：The book was read by him. （这本书被他读了。）- 谓语动词“was read”与主语“book”的单数一致。The books were read by him. （这些书被他读了。）- 谓语动词“were read”与主语“books”的复数一致。