当句子的主语和谓语呈被动关系，即主语是动作的承受者时(相对于执行者)，谓语要用被动语态。具体说来，被动语态主要用于以下两种情况：

　　1.不知道或没有必要说明动作的执行者。

　　Printing was introduced into Europe from China.

　　Such books are written for children.

　　Everything has been taken away.

　　When will the museum be opened for the public?

　　I was born in 1980.

　　2.动作的承受者是谈话的中心。

　　The composition was written with great care.

　　These questions are settled through negotiation.(negotiation 谈判)

　　The flowers will be planted next week.

　　He is said to be a good teacher.

　　For this he was often made fun of.(make fun of 开玩笑)

　　若要同时将动作的执行者表达出来，往往可以在执行者前面加上by.

　　I'm puzzled by what the teacher has said.

　　The door was locked by me when I left the room last night.

　　The construction of the road has been held up by a flood.(hold up 阻碍、阻挡)

　　He was sent to school by his parents when he was only five years old.