一、 当句子的主语是动作的执行者时，谓语的形式叫主动语态。当句子的主语是动作的承受者时，谓语的形式叫被动语态。被动语态由助动词be +过去分词构成，时态通过 be 表现出来。例如：
1 一般现在时：You are required to do this.
2 一般过去时：The window was broken by Xiao Ming.
3 一般将来时：The problem will be discussed tomorrow.
4 现在进行时：The road is being widened.
5 过去进行时：The new tool was being made.
6 现在完成时：The door has been painted.
7 过去完成时：He said that the work had been finished.
8 过去将来时：He said that the trees would be planted.
二、一些特殊的被动结构
1 、带情态动词的被动结构：
The problem must be solved soon. 这个问题必须尽快解决。
2 、带不定式的被动结构：
Betty has never been heard to speak ill of others. 从未听到贝蒂说别人坏话。
This task needs to be done with great care.这项工作必须认真去做。
3 、短语动词的被动结构：
短语动词的被动结构有以下几种：
1)(不及物)动词+介词：若这类短语动词是及物的，则可用于被动语态，如：look at, look after, talk about, think of 等。若这类短语动词是不及物的，则不可用于被动语态，如：look up, look down 等。
His plan was well thought of. 他的计划受很高评价。
2)(及物)动词+副词：bring about, carry out, find out, make out, put away, put off, take up, turn down, turn out, wipe out 等。
The secret was soon found out. 秘密很快被查出。
3)动词+副词+介词：do away with, face up to, give in to, look down upon, make up for, put up with 等。
Nobody likes to be looked down upon. 没有人喜欢受歧视。
4)动词+名词+介词：catch sight of, keep an eye on, fix one’s eyes upon, make a fool of, make use of, pay attention to, put an end to, set fire to, take notice of 等。
Every use should be made of our spare time. 我们应当充分利用业余时间。
Your pronunciation must be paid attention to. 你应该注意发音。
4 、带复合宾语的被动结构。动词在改为被动语态时，一般把主动结构中的宾语改成主语，宾语补足语保留在谓语后面。例如：
We always keep the classroom clean. --- The classroom is always kept clean.
5 、主动形式表示被动意义的常见词有：
1)动词want, need, require 后用动名词的主动式，这时，动名词和句中主语有动宾关系，而不定式需用被动式。例如：
The children need looking after/.to be looked after. 孩子们需要照顾。
The window wants cleaning/to be cleaned. 窗户需要清洗。
2)有些及物动词后须加副词(如well, easily 等)有些可不加如act, clean, cut, draw, keep, lock, open, play, read, sell, shut, strike, wash, write, measure, weigh 等。例如：
The cloth washes/sells well. 这布很经洗(很畅销)。
The door won’t shut. 这门关不上。The play won’t act.这戏不宜上演。
The street measures twenty meters wide. 街道宽20米。
3) 形容词 worth 后直接加动名词时。例如：
The book is worth reading a second time.这本书值得再次阅读。
4)某些作表语的形容词后用不定式主动式表示被动意义。例如：
The fish is not fit to eat.这种鱼不宜食用。
5)某些感官动词和系动词(如feel, look, prove, smell, sound, taste, wear 等)与形容词连用时。如：
The body of a hibernating animal feels very cold. 冬眠动物的身体摸上去很凉。
The dish tastes delicious.这道菜尝起来非常可口。
6、 以下动词构成的句子不能改为被动句：
1)动词 leave, enter, reach 等的宾语是表示处所、地点等。
He left hometown when he was five. 他五岁时就离开了家乡。
He entered the office without being permitted. 他未经许可就进了办公室。
2)表示状态的动词如 become, benefit, cost, contain, equal, fit, fail, have, lack, last, mean, suit, look like 等。
Two added to five equals seven. 二加五等于七。
Mary looks much like her mother. 玛丽看起来非常象她母亲。
3)以下不及物动词及短语动词：appear, belong to, break out, die, happen, lie, occur, rise, take place, agree with, consist of, have on, keep up with 及一些固定词组，如keep words, lose heart, make a face 等。
China is a developing country belonging to the third world. 中国是个发展中国家，属于第三世界
Don’t lost heart, and you will succeed sooner or later. 不要灰心，你迟早会成功的。
Do you know the story taking place in our class? 你知道我们班发生的故事吗?
4)宾语是反身代词，相互代词，同源宾语，不定式，动名词，抽象名词等。
He admired himself long in the mirror.他长时间地打量着镜子中的自己。
We are now living a happy life.我们现在过着幸福生活。
The moment they got home, it began to snow.他们刚一到家，天就下起雪来。
7、 汉语有一些句子不出现主语，在英文中一般可用被动结构表示。例如：
据说--- It is said that... 希望--- It is hoped that...
有人相信--- It is believed that... 众所周知---It is known that...
大家认为--- It is considered that... 拒推测--- It is supposed that...
It is said that he is very rich.--- He is said to de very rich. 据说他很富有。
8 、被动语态除了be +过去分词以外还有 get +及物动词过去分词形式。例如：
I tried to find my way through the forest without a map and got lost. 我试图不带地图在森林中通过，结果迷了路。
The girl is to be get married to a rich businessman. 这位女士打算嫁给一位富商。
