一、主动语态
主语是谓语动作的使动方。也就是说谓语的动作源自主语，而施加于宾语。相反，被动语态中，主语是谓语动作的受动方，如果有宾语的，宾语往往是谓语动作的使动方。 在语法机构上，主动语态和被动语态的区别主要在于，主动语态直接使用动词原形作为谓语，然后再在该动词原形的基础上施加时态和其他语法；而被动语态则使用系词+动词的过去分词作为谓语，各种时态和其他语法也施加在系词上。
二、被动语态
英语中的被动语态使用得比汉语要多，要普遍，许多课本及考试乃至实际应用中都常常涉及到这个问题。一般说来，当强调动作承受者，不必说出执行者或含糊不清的执行者时，多用被动式。须注意的是，许多地方与汉语不同。注意那些汉语中没有"被……"的意思，英语却应该用被动态。还要注意，英语的被动态往往由"by"引出，而有用介词"by"的短语往往又不是被动态，而是系表结构。还有些特殊现象，如：known to man(人类......所知)，on foot步行(美国人有时用by foot)，in carraige(乘四轮马车)等等。
还有假主动，真被动的十几个常用词的用法，以及so heavy to carry而不用so heavy to be carried 等习惯用法。有关这类情况，做到心中有数对全面掌握被动态，en211 准确解答习题非常关键，被动态必须涉及的是动词的各种时态变化的问题。英语的时态本来很复杂，怎样记住各自的被动形式呢? 首先要明确"将来进行无被动，现在完成进行同"。这两种时态无被动形式。
另外，不及物动词带有同源宾语的动词，反身代词的动词和系动词都无被动形式。即便如此，还有不定式，动名词，分词，以及它们的复合结构)的被动态，再加上情态动词，助动词以及它们的疑问式和否定式从中掺杂，真是令人头痛，眼花缭乱。下面口诀就以动词do为例，即do did过去式done过去分词，以口诀形式总结各种时态的被动态，一定对你有所启示。 被动语态的句子通常是以Be-Passive(即"be+过去分词")的`形式来表达，但也可以Get-Passive(即"get+过去分词")的形式来表达，例如：He got punished today. Get-Passive是一种新兴的被动语态形式；相对来说它的使用还没有Be-Passive那么广泛，一般限于口语和非正式书面语；但它却有着用得愈来愈多的趋势，是一种生气蓬勃的语言现象。 如果要特别强调动作或行为的执行者时，句子后面需接by～，译为“被（由）……”。
1 被动语态的句型 肯定句：主语+be +过去分词+（by～）. 否定句：主语+be not +过去分词+（by～）. 一般疑问句：Be +主语+过去分词+（by～）？ 特殊疑问句：疑问词+be +主语+过去分词+（by～）？ 被动语态的时态是由be的时态决定的，be是什么时态，全句就是什么时态，be动词后面的过去分词不变。
一、 被动语态的用法：
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. I am asked to study hard. Knives are used for cutting things.
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. Dinosaur eggs were laid long long ago.
3. 一般将来时的被动语态构成：will+ be + 及物动词的过去分词 A new hospital will be built in our city. Many more trees will be planted next year.
4. 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. They are planting trees over there. → Trees are being planted over there by them.
5. 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. Many man-made satellites have been sent up into space by many countries.
6.过去进行时的被动语态构成：was/were + being + 及物动词的过去分词 The boy was being operated on when his parents hurried to the hospital. The new road was being made.
7.过去完成时的被动语态构成：had + been + 及物动词的过去分词 The classroom hadn’t been cleaned before the teacher came. The tickets had been sold out berore I came to the cinema.
8.将来完成时的被动语态构成：shall/will + have done They will have been married for 20 years by then. The project will have been completed before May.
9.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. Your mistakes should be corrected right now. The door may be locked inside. Your homework can be handed in tomorrow.
二、 怎样把主动语态改成被动语态?
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
