被动语态
1．何时运用被动语态：
（1）强调动作的接受者：America was discovered by Columbus.
（2）不知谁是动作的执行者：You are wanted on the phone.
（3）作客观说明：It is said that the meeting has been put off.（经典句型）
2．主动变被动的基本方法：（说起来容易，掌握起来需要用心！）
（1）主动语态中的宾语变为被动语态的主语。
（2）谓语动词变为由“be 过去分词”的形式，配合时态作相应变化。
（3）主动语态主语置于介词 by之后，如无必需，则省略。
（4）不及物动词没有被动语态。
现 在 do (does) →am / is / are done
We keep the piano in the living-room.
→The piano is kept in the living-room.
过 去 did→was / were done
They built the bridge in 1980.
→The bridge was built in 1980.
将 来 shall shall
will do → will be done
He will read the book tomorrow.
→The book will be read tomorrow.
现在完成 have have
has done → has been done
We have delivered the newspaper.
→The newspapers have been delivered (by us).
过去完成 had done → had been done
She had seen the film before she came here.
→The film had been seen before she came here.
将来完成 shall shall
will have done → will have been done
By the end of this term we shall have finished 80 texts.
→By the end of this term 80 texts will have been finished.
现在进行 am am
is doing → is being done
are are
They are drawing the picture.
→The picture is being drawn by them.
过去进行 was doing → was being done
were were
He was reviewing their lessons at this moment yesterday.
→Their lessons were being reviewed at this moment yesterday.
情态动词 may may
can can
must must
should do → should be done
ought to ought to
used to used to
You must write an article on the subject.
→An article must be written on the subject.
平行结构
许多句子在描述一个人或一件物品时往往会出现一系列修饰语；动词的修饰语， 即副词往往也会几个同时使用，构成平行结构，平行结构要求语法结构须保持一致，如：
1．系列动词：
after school, we sang, danced and played the piano in the classroom.
2．系列形容词：
She is slim, tall, blond and beautiful.
3．系列副词：
The students are listening to me carefully and eagerly.
平行结构不仅包括动词，形容词，副词，也包括分词，不定式，动名词，名词短语和句子等的平行用法，务必提高辨别力。
