一、 當句子的主語是動作的執行者時，謂語的形式叫主動語態。當句子的主語是動作的承受者時，謂語的形式叫被動語態。被動語態由助動詞be +過去分詞構成，時態通過 be 表現出來。例如：
1 一般現在時：You are required to do this.
2 一般過去時：The window was broken by Xiao Ming.
3 一般將來時：The problem will be discussed tomorrow.
4 現在進行時：The road is being widened.
5 過去進行時：The new tool was being made.
6 現在完成時：The door has been painted.
7 過去完成時：He said that the work had been finished.
8 過去將來時：He said that the trees would be planted.
二、一些特殊的被動結構
1 、帶情態動詞的被動結構：
The problem must be solved soon. 這個問題必須盡快解決。
2 、帶不定式的被動結構：
Betty has never been heard to speak ill of others. 從未聽到貝蒂說別人壞話。
This task needs to be done with great care.這項工作必須認真去做。
3 、短語動詞的被動結構：
短語動詞的被動結構有以下幾種：
1)(不及物)動詞+介詞：若這類短語動詞是及物的，則可用于被動語態，如：look at, look after, talk about, think of 等。若這類短語動詞是不及物的，則不可用于被動語態，如：look up, look down 等。
His plan was well thought of. 他的計劃受很高評價。
2)(及物)動詞+副詞：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)動詞+副詞+介詞：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. 沒有人喜歡受歧視。
4)動詞+名詞+介詞：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. 我們應當充分利用業余時間。
Your pronunciation must be paid attention to. 你應該注意發音。
4 、帶復合賓語的被動結構。動詞在改為被動語態時，一般把主動結構中的賓語改成主語，賓語補足語保留在謂語后面。例如：
We always keep the classroom clean. --- The classroom is always kept clean.
5 、主動形式表示被動意義的常見詞有：
1)動詞want, need, require 后用動名詞的主動式，這時，動名詞和句中主語有動賓關系，而不定式需用被動式。例如：
The children need looking after/.to be looked after. 孩子們需要照顧。
The window wants cleaning/to be cleaned. 窗戶需要清洗。
2)有些及物動詞后須加副詞(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. 這布很經洗(很暢銷)。
The door won’t shut. 這門關不上。The play won’t act.這戲不宜上演。
The street measures twenty meters wide. 街道寬20米。
3) 形容詞 worth 后直接加動名詞時。例如：
The book is worth reading a second time.這本書值得再次閱讀。
4)某些作表語的形容詞后用不定式主動式表示被動意義。例如：
The fish is not fit to eat.這種魚不宜食用。
5)某些感官動詞和系動詞(如feel, look, prove, smell, sound, taste, wear 等)與形容詞連用時。如：
The body of a hibernating animal feels very cold. 冬眠動物的身體摸上去很涼。
The dish tastes delicious.這道菜嘗起來非常可口。
6、 以下動詞構成的句子不能改為被動句：
1)動詞 leave, enter, reach 等的賓語是表示處所、地點等。
He left hometown when he was five. 他五歲時就離開了家鄉。
He entered the office without being permitted. 他未經許可就進了辦公室。
2)表示狀態的動詞如 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. 瑪麗看起來非常象她母親。
3)以下不及物動詞及短語動詞：appear, belong to, break out, die, happen, lie, occur, rise, take place, agree with, consist of, have on, keep up with 及一些固定詞組，如keep words, lose heart, make a face 等。
China is a developing country belonging to the third world. 中國是個發展中國家，屬于第三世界
Don’t lost heart, and you will succeed sooner or later. 不要灰心，你遲早會成功的。
Do you know the story taking place in our class? 你知道我們班發生的故事嗎?
4)賓語是反身代詞，相互代詞，同源賓語，不定式，動名詞，抽象名詞等。
He admired himself long in the mirror.他長時間地打量著鏡子中的自己。
We are now living a happy life.我們現在過著幸福生活。
The moment they got home, it began to snow.他們剛一到家，天就下起雪來。
7、 漢語有一些句子不出現主語，在英文中一般可用被動結構表示。例如：
據說--- It is said that... 希望--- It is hoped that...
有人相信--- It is believed that... 眾所周知---It is known that...
大家認為--- It is considered that... 拒推測--- It is supposed that...
It is said that he is very rich.--- He is said to de very rich. 據說他很富有。
8 、被動語態除了be +過去分詞以外還有 get +及物動詞過去分詞形式。例如：
I tried to find my way through the forest without a map and got lost. 我試圖不帶地圖在森林中通過，結果迷了路。
The girl is to be get married to a rich businessman. 這位女士打算嫁給一位富商。
