语态表示主语和谓语的关系。语态有两种：主动语态和被动语态。如果主语是动作的执行者，或者是说动作是由主语完成的，要用主动语态，如：We speak Chinese in China.在中国我们说汉语；如果主语是动作的承受者，或者是说动作不是由主语而是由其他人完成的，则用被动语态，如：Chinese is spoken by us in China.在中国汉语被我们说。
一、主动语态改成被动语态方法
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. 将主动语态的宾语作被动语态的主语；
2. 谓语动词变为“be+及物动词的过去分词”，并通过be的变化来表达出不同的时态；
3主动语态的主语变为介词by的宾语，组成介词短语放在被动结构中的谓语动词之后。（有时by的短语可以省略）；
例：1. Bruce writes a letter every week. →A letter is written by Bruce every week.
二、被动语态的用法：
1. 一般现在时的被动语态构成：is / am / are + 及物动词的过去分词
Our classroom is cleaned everyday.
2. 一般过去时的被动语态构成：was / were + 及物动词的过去分词
A new shop was built last year.
3. 现在完成时的被动语态构成：has / have + been + 及物动词的过去分词
This book has been translated into many languages.
4. 一般将来时的被动语态构成：will+ be + 及物动词的过去分词
Many more trees will be planted next year.
5. 含有情态动词的被动语态构成：情态动词+ be + 及物动词的过去分词
Young trees must be watered often.
6. 现在进行时的被动语态构成：am / is / are + being + 及物动词的过去分词
Uncle Wang is mending my bike now.→ My bike is being repaired by Tom now.
7. 不定式的被动语态：to + be + 及物动词的过去分词
There are two books to be read. → There are twenty more trees to be planted.
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
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.（www.yingyuzuowen.cn）
He showed me a ticket.→A ticket was shown to me by him.
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 laughed at by us.
常见考法
对于语态考查，多以单选、词语运用的形式考查学生在具体语境中灵活运用被动语态的能力。一般情况下，会综合考查时态和语态，这时，要根据语境和动作发生的时间来确定时态，然后再确定语态。
典型例题：-Could you tell me whom the radio__________by? -Sorry. I have no idea.
A invents B invented C is invented D was invented
解析：题干的意思是“你能告诉我收音机是谁发明的吗？”，发明收音机是过去的事，所以用过去时，排除 A和C；而radio和invent 构成被动关系，应用被动语态，排除B
答案：D
误区提醒
有些动词后跟不带to的不定式作宾语补足语，但改为被动结构后要加上“to”，这一点我们必须注意。
典型例题：The young man was often seen _____ by the lake.
A to draw B to drawing C draw D drew
解析：这是2007年济南的中考题。“看到某人做某事”为see sb.do sth.。句中动词原形是省略to的不定式，在被动语态中要还原to.
答案：A