把主动语态改为被动语态非常简单，可以遵循以下几个步骤：
1. 先找出谓语动词；
2. 再找出谓语动词后的宾语；
3. 把宾语用作被动语态中的主语；
4. 注意人称、时态和数的变化。
例：1. Bruce writes a letter every week. →A letter is written by Bruce every week.
2. Li Lei mended the broken bike this morning.→The broken bike was mended by Li Lei this morning.
3. He has written two novels so far.→Two novels have been written by him so far.
4. They will plant ten trees tomorrow.→Ten trees will be planted by them tomorrow.
5. Lucy is writing a letter now.→A letter is being written by Lucy now.
6. You must lock the door when you leave.→the door must be locked when you leave.
三、 使用被动语态应注意的几个问题：
1. 不及物动词无被动语态。
What will happen in 100 years.
The dinosaurs disappeared about 65 million years ago.
2. 有些动词用主动形式表示被动意义。
This pen writes well.
This new book sells well.
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 at him. →He can’t be laugh at 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.
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