掌握主动句与被动句互转的方法，是做句型转换题的基础。
要点讲解
- 主动变被动步骤：1）主动句宾语变被动句主语；2）谓语动词变 be + 过去分词（be 随时态变）；3）主动句主语变 by 短语（可省略）。
- They clean the room every day. → The room is cleaned（by them）every day.
- 时态保持：He wrote a letter. → A letter was written（by him）.
- 含情态动词：You must finish the work. → The work must be finished（by you）.
- 双宾语转换：give sb. sth. → sb. be given sth. 或 sth. be given to sb.：My mother gave me a book. → I was given a book by my mother. / A book was given to me by my mother.
- 带复合宾语：They made him monitor. → He was made monitor（by them）.
- 被动变主动：主语+be+done+by+sb. → sb.+谓语（原时态）+宾语：The bike was repaired by Tom. → Tom repaired the bike.
- 主动句主语是代词时变被动要去掉 by 短语：I cleaned the room. → The room was cleaned（by me 可省）。
经典例句
- The workers are building a new bridge. → A new bridge is being built by the workers.
工人们正在建一座新桥。→ 一座新桥正在被工人们建造。 - We should protect the environment. → The environment should be protected.
我们应该保护环境。→ 环境应该被保护。 - She gave me a present. → I was given a present（by her）.
她给了我一份礼物。→ 我被（她）给了一份礼物。
易错提醒
- 转换时注意：时态不能变；及物动词才有被动；不及物动词（happen, take place）无被动。