被动语态是由助动词be＋过去分词的形式构成的！例如：主动句： The naughty boy broke the window yesterday.(昨天这个淘气的小男孩打破了这扇窗户）
改成被动句为：The window was broken by the naughty boy yesterday.（昨天这扇窗户被这个小男孩打破了）
被动语态中宾语提前做主语后面按照主谓宾顺装It is said tha some very big bridges have been bulit in your country in recent years.被Some very big bridges are said that to have been bulit in your country in recent years.主
