3. 感官动词或使役动词使用省略to的动词不定式，主动语态中不带to ，但变为被动语态时，须加上to 。

例：make somebody do something

　　→somebody+ be +made to do something

see somebody do something

　　→somebody +be +seen to do something

A girl saw my wallet drop when she passed by.

　　→My wallet was seen to drop by a girl when she passed by.

The boss made the little boy do heavy work.

　　→The little boy was made to do heavy work by the boss.

4. 如果是接双宾语的动词改为被动语态时，直接宾语(物)作主语，那么动词后要用介词，这个介词是由与其搭配的动词决定。

He gave me a book.

　　→A book was given to me by him.

He showed me a ticket.

　　→A ticket was shown to me by him.

My father bought me a new bike.

　　 →A new bike was bought for me by my father.

5. 一些动词短语用于被动语态时，动词短语应当看作一个整体，而不能丢掉其中的介词或副词。

We can't laugh him.

　　→He can't be laugh by us.

He listens to the radio every day.

　　 →The radio is listened to by him every day.

The nurse is taking care of the sick man.

　　→The sick man is being taken care of by the nurse.

只要你掌握了以上一些方法，

使用被动语态的一般因由

1. 不易说出动作或状态的「发出者」