将主动语态的宾语变为被动语态的主语,将主动谓语变为被动谓语(be+过去分词),将主动语态的主语变为by短语(在被动句中用作状语).如：
He broke the cup.→ The cup was broken by him.
一般疑问句变为被动语态的方法,其实就是陈述句变被动语态的一般疑问句形式.如：
Did he break the cup?→ Was the cup broken by him?