it作形式主语是什么?
动词不定式、动名词短语起、从句在句子中起主语作用，而这一部分用词较多时，可以用it作为形式主语，放在句首代表其后所说的事实上的、真正的主语，而把真正的主语放在后面。
1、It +谓语＋动词不定式。It作形式主语，动词不定式作真正的主语。例如：It is difficult to climb a mountain.爬山是很艰难的。It’s a good habit to do morning exercises.作早操是个好习惯。It’s important to do proper memory work in the study of a foreign language.在学习外语时适当地做一些有助于记忆的练习是很重要的。It is right to do so.这样做是对的。
2、It＋谓语＋动名词短语。It作形式主语，动名词短语作真正的//www.souquanme.com主语。例如：It is dangerous playing with fire.玩火是危险的。It is no use learning without thinking.学而不思则罔。It’s useless arguing with a silly boy.和笨孩子争论是没有用的。
3、It＋谓语＋名词性从句。It作形式主语，以that引导的名词性从句是真正的主语。例如：It is a pity that you didn’t see such a good film.你没看这么好的电影，真可惜。It is certain that we shall succeed.我们一定会成功。
It is strange that nobody knows where he lives.真奇怪，谁也不知道他住在哪里。（It is strange that…后面可用虚拟语气。如：It is strange that he should have made such a mistake.他居然犯了这样一个错误，真奇怪。It is strange that nobody should know where he lives.居然没有人知道他住在哪里，真奇怪。）
It is said that the plane will take off at ten tomorrow morning.据说飞机明天上午十点起飞。
初一英语语法
如would后面+动词原形！定义
动名词是一种兼有动词和名词特征的非限定动词。它可以支配宾语，也能被副词修饰。动名词有时态和语态的变化。
解释：动词的ing形式如果是名词，这个词称动名词。
一、动名词的作用
动名词具有名词的性质，因此在句中可以作主语、表语、宾语、定语等。
1、作主语
Reading is an art. 读书是一种艺术。
Climbing mountains is really fun. 爬山是真有趣。
Working in these conditions is not a pleasure but a suffer. 在这种工作条件下工作不是愉快而是痛苦。
动名词作主语，有时先用it作形式主语，把动名词置于句末。这种用法在习惯句型中常用。如：
It is no use/no good crying over spilt milk. 洒掉的牛奶哭也没用。
It is a waste of time persuading such a person to join us. 劝说这样的人加入真是浪费时间。
It was hard getting on the crowded street car. 上这种拥挤的车真难。
It is fun playing with children. 和孩子们一起玩真好。
There is no joking about such matters. 对这种事情不是开玩笑。
动名词作主语的几种类型
动名词可以在句子中充当名词所能充当的多种句子成分。在这里仅就动名词在句子中作主语的情况进行讨论。
动名词作主语有如下几种常见情况：
1. 直接位于句首做主语。例如：
Swimming is a good sport in summer.
2. 用 it 作形式主语，把动名词(真实主语)置于句尾作后置主语。
动名词做主语时，不太常用 it 作先行主语，多见于某些形容词及名词之后。例如：
It is no use telling him not to worry.
常见的能用于这种结构的形容词还有：better，wonderful，enjoyable，interesting，foolish，difficult，useless，senseless，worthwhile，等。
注意：important，essential，necessary 等形容词不能用于上述结构。
3. 用于“There be”结构中。例如：
There //www.souquanme.comis no saying when he'll come.很难说他何时回来。
4. 用于布告形式的省略结构中。例如：
No smoking ( =No smoking is allowed (here) ).
No parking.
5. 动名词的复合结构作主语
当动名词有自己的逻辑主语时，常可以在前面加上一个名词或代词的所有格，构成动名词的复合结构(——这时，名词或代词的所有格做动名词的逻辑主语)。动名词的复合结构也可以在句中作主语。例如：
Their coming to help was a great encouragement to us.
6.例词
shopping fishing cycling这些都是很常见的动名词
二、动名词作主语与动词不定式作主语的比较
动词不定式和动名词都可以用作主语。在意义上相近。但动名词多用来表示泛指或抽象动作，不定式多用来表示特指或具体动作。比较：
Smoking is not good for health.
It is not good for you to smoke so much.
注意：
1)在口语中，用动名词作主语位于句首的较不定式多见。
2)在“It is no use...”，“It is no good...”，“It is fun...”，“It is a waste of time...”等句型中，通常用动名词作真实主语：
It is no use/good/a waste of time talking about that.
*It is no use/good/a waste of time to talk about that.
3)在疑问句中，通常用动名词的复合结构，而不用不定式的复合结构作主语：
Does your saying that mean anything to him?
*Does for you to say that mean anything to him?
4)在“There be”句型中，只能用动名词，而不能用不定式作主语：
There is no telling what will happen.
It is impossible to tell what will happen.
5)当句子中的主语和表语都是非限定动词时，要遵循前后一致的原则，主语和表语在形式上要求统一：
Seeing is believing.
*To see is to believe.
2、作宾语
（1）作动词的宾语
某些动词后出现非限定性动词时只能用动名词作宾语，不能用不定式。常见的此类动词有：advise, allow, permit, avoid, consider, enjoy, finish, give up, cannot help, imagine, include, keep, keep on, mind, miss, put off, delay, practise, resist, suggest, depend on, think about, set about, succeed in, worry about, burst out, insist on, can’t stand, be used to, get used to, devote…to…, look forward to, pay attention to, get down to等。如：
They went on walking and never stopped talking. 他们继续走，说个不停。
I found it pleasant walking along the seashore. 在海滩上走真是乐事。
（2）作介词的宾语
We are thinking of making a new plan for the next term. 我们正考虑为下学期制定新的计划。
Shall we have a rest or get down to doing our work? 我们休息呢还是开始干活？
（3）作形容词的宾语
The music is well worth listening to more than once. 这种曲子很值得多听几遍。
We are busy preparing for the coming sports meet. 我们正为马上到来的运动会忙着做准备。
3、作表语
动名词作表语时句子主语常是表示无生命的事物的名词或what引导的名词性从句。表语搜趣网动名词与主语通常是对等的关系，表示主语的内容，主语、表语可互换位置。
Your task is cleaning the windows. 你的任务就是擦窗户。(Cleaning the windows is your task.)
What I hate most is being laughed at. 我最痛恨的就是被别人嘲笑。 (Being laughed at is what I hate most.)
4、作定语
动名词作定语往往表示被修饰词的某种用途。如：
a walking stick ＝a stick for walking=a stick which is used for walking
a washing machine=a machine for eVIHuUwashing=a machine which is used for washing
a reading room=a room for reading=a room which is used for reading
a measuring tape=a tape for measuring=a tape which is used for measuring
sleeping pills=pills for sleeping=pills which is used for sleeping
二、动名词的逻辑主语
带有逻辑主语的动名词称为动名词的复合结构。当动名词的逻辑主语与句子的主语不一致时，要在动名词之前加上物主代词或名词所有格，这便构成了动名词的复合结构。其中物主代词（名词所有格）是逻辑上的主语，动名词是逻辑上的谓语。动名词复合结构在句中可作主语、宾语、表语等，分别相当于一个主语从句、宾语从句、表语从句。如：
Her coming to help encouraged all of us. 他来帮忙鼓舞了我。 (=That she came to help encouraged all of us.)
Jane’s being careless caused so much trouble. 简这么粗心惹来了不少麻烦。 (=That Jane was careless caused so much trouble.)
What’s troubling them is their not having enough food. 烦扰他们的是食物不足。 (=What’s troubling them is that they have not enough food.)
在口语中，如果动名词复合结构作宾语，其中的物主代词常用人称代词宾格，名词所有格常用名词普通格来代替，但在句首作主语时不能这样来代替。如：
Would you mind my/me using your computer? 用下你的电脑介意吗？
The father insisted on his son’s/his son going to college. 爸爸坚决要求儿子上大学。
Mary’s (不可用Mary) being ill made her mother upset. 玛丽病了，使她妈妈很着急。
His (不可用Him)smoking made his family angry. 他抽烟使他一家人非常生气。
在下列情况下动名词的逻辑主语必须用名词的普通格或人称代词宾语：
a.无命名词
The baby was made awake by the door suddenly shutting. 这个婴儿被猛烈的关门声吵醒。
b. 有生命名词但表示泛指意义
Have you ever heard of women practising boxing? 你听说过妇女练拳击吗？
c. 两个以上的有生命名词并列
Do you remember your parents and me telling about this? 你记得你父母和我都告诉过你这事吗？
三、动名词的时态和语态
动名词的时态和语态如下：
时态
主动语态
被动语态
一般式
writing
being written
完成式
having written
having been written
其否定形式是在doing前加上not
1、动名词一般式表示的动作通常是一般性动作，即不是明确地发生在过去、现在或将来的动作，或是与谓语动词所表示的动作同时发生的动作。如：
I hate talking with such people. 我讨厌与这样的人说话。
Being careless is not a good habit. 粗心不是一个好习惯。
2、动名词的完成式表示的动作发生在谓语动词动作之前。如：
I don’t remember having met him before. 我记不得以前见过他。
Thank you for having taking so much trouble to help. 谢谢你费力帮忙。
3、动名词的逻辑主语同时也是动名词动作的承受者，动名词用被动语态。
（1）它的一般式表示的动作与谓语动词动作同时发生，或在其前发生。如：
I don’t like being laughed at in public. 在公共场合下，我不喜欢被别人嘲笑。
（2）它的完成式表示的动作发生在谓语动词之前。如：
I am very pleased at your having been honoured with a medal. 我很高兴你能获得这样的奖牌。
（3）在某些动词，我们常用动名词的一般式表示完成式，尽管动作发生在谓语动词动作之前，这似乎是一种强大的习惯。如：
Excuse me for being late. 我来晚了请你原谅。
I don’t remember ever meeting somewhere. 我记不得原来在什么地方见过。
Thank you for giving us so much help. 谢谢给我们这么大的帮助。
（4）在多数情况下都避免使用动名词被动语态完成式，而用一般式代替，以免句子显得累赘，尤其是在口语中。如：
I forget once being taken (having been taken ) to the city zoo. 我曾被带到过这个动物园，可我忘了。
（5）动名词被动语态一般式与现在分词被动语态一般式同形，但无进行意义，being不可省略。如：
She is afraid of being taken to the public. 她怕被领到大众面前。
四、常见题型：
1） 动名词做主语时，谓语动词为单数
2） 在动名词和不定式中，作为介词的宾语是动名词
3） 动名词的否定直接在其前加否定词，通过代词的宾格或所有格形式给出逻辑主语
例：
I would appreciate_______ back this afternoon.
A．you to call B．you call C．you calling D．you’re calling（Key：C；换成your calling也对）
4） 有些词后只能接动名词
admit; appreciate; avoid; celebrate; consider; contemplate; defer; delay; deny; detest; discontinue; dislike; dispute; enjoy; it entails; escape; excuse; explain; fancy; feel like; finish; forgive; can’t help; hinder; imagine; it involves; keep; it means; mention; mind; miss; it necessitates; pardon; postpone; practice; prevent; recall; report; resent; resist; risk; suggest; understand...
5） 另外还有一些接-ing形式的常用说法
it’s no good; it’s no/little/hardly any/ use; it’s not/hardly/scarcely use; it’s worthwhile; spend money/time; there’s no; there’s no point in; there’s nothing worse than; what’s the use/point...
6） 有些词后面加不定式和动名词均可
remember, forget, try, stop, go on, cease, mean后面均可用不定式和-ing形式，但意义截然不容。
例：
remember to do/doing：
①I remembered to post the letters.（指未来/过去未来将要做的动作）
②I remembered posting/having posted the letters.（我记得做过这个动作）
forget与remember的用法类似。
regret的用法：
①I regret to inform you that…（我很遗憾地通知你……）
②I regretted having left the firm after twenty years.（为了“二十年前的离开”而遗憾。）
try to（努力）与try +–ing（试验）：
①You really must try to overcome your shyness.
②Try practicing five hours a day.
五、动名词与现在分词的同与不同
动名词它在形式上与现在分词相同，都是在动词原形的词末加-ing。在现代语法中，这两种形式同视为"-ing形式"。 这两种形式的另一个相同之处是：它们都是由动词变化而成的，它们都保留了动词的某些特征，它们都能带自己的宾语、状语，而构成动名词短语或是现在分词短语去担当句子成分。例如：
Speaking in the public , he will surely be very cheerful .
（现在分词短语，作状语）他在公众场所讲话时总是兴高采烈的。
She hates speaking in the public.
（动名词短语，作宾语）她不喜欢在公众场所讲话。
区别：
1､动名词和现在分词都可以用于系动词之后作表语,区别方法是:
①作表语的动名词与主语指的是同一件事,此时系动词相当于“是”,通常把主语和表语的位置互换,语法和意思不变,例如:
My hobby is swimming.可改为Swimming is my hobby.(可将原句中的主语与表语位置互换)
②现在分词作表语主要用以说明主语的性质,不能与主语互换位置,例如:
The story is interesting .不可改为:Interesting is the story.
2､动名词和现在分词都可以用作定语来修饰名词,两者的区别在于:
动名词修饰名词时主要表示该名词的用途,而现在分词修饰名词时性质､状态或动作等｡试比较:
①a swimming boy和a swimming suit
前者的意思是“一个正在游泳的男孩”,即a boy who is swimming ,现在分词swimming 表示被修饰名词boy的动作;而后者的意思是“游泳衣”,即a suit for swimming , 动名词swimming表示suit 的用途｡
②a sleeping child 和 a sleeping car
前者的意思是“一个正在睡觉的孩子”,即a child who is sleeping ,现在分词sleeping 表示被修饰名词 child 正处于的状态;而后者的意思是“卧车(被用来睡觉的车厢)”,即 a car which is used for sleeping ,动名词 sleeping 表示car 的用途｡
被动语态
一、 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.
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. 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.
4. 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.
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.
Your mistakes should be corrected right now.
The door may be locked inside.
Your homework can be handed in tomorrow.
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.
They are planting trees over there. →
Trees are being planted over there by them.
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.
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,或是间接宾语加被动语态再加只接宾语。
He gave me a book.→A book was given to me by him. 或是I was given a book by him.
He showed me a ticket.→A ticket was shown to me by him. 或是i was shown a ticket by him.
My father bought me a new bike. →A new bike was bought for me by my father. 或是Lwas bought a new bike 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 him. →He can’t be laugh 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.</CA>
动名词是一种兼有动词和名词特征的非限定动词。它可以支配宾语，也能被副词修饰。动名词有时态和语态的变化。
解释：动词的ing形式如果是名词，这个词称动名词。
一、动名词的作用
动名词具有名词的性质，因此在句中可以作主语、表语、宾语、定语等。
1、作主语
Reading is an art. 读书是一种艺术。
Climbing mountains is really fun. 爬山是真有趣。
Working in these conditions is not a pleasure but a suffer. 在这种工作条件下工作不是愉快而是痛苦。
动名词作主语，有时先用it作形式主语，把动名词置于句末。这种用法在习惯句型中常用。如：
It is no use/no good crying over spilt milk. 洒掉的牛奶哭也没用。
It is a waste of time persuading such a person to join us. 劝说这样的人加入真是浪费时间。
It was hard getting on the crowded street car. 上这种拥挤的车真难。
It is fun playing with children. 和孩子们一起玩真好。
There is no joking about such matters. 对这种事情不是开玩笑。
动名词作主语的几种类型
动名词可以在句子中充当名词所能充当的多种句子成分。在这里仅就动名词在句子中作主语的情况进行讨论。
动名词作主语有如下几种常见情况：
1. 直接位于句首做主语。例如：
Swimming is a good sport in summer.
2. 用 it 作形式主语，把动名词(真实主语)置于句尾作后置主语。
动名词做主语时，不太常用 it 作先行主语，多见于某些形容词及名词之后。例如：
It is no use telling him not to worry.
常见的能用于这种结构的形容词还有：better，wonderful，enjoyable，interesting，foolish，difficult，useless，senseless，worthwhile，等。
注意：important，essential，necessary 等形容词不能用于上述结构。
3. 用于“There be”结构中。例如：
There //www.souquanme.comis no saying when he'll come.很难说他何时回来。
4. 用于布告形式的省略结构中。例如：
No smoking ( =No smoking is allowed (here) ).
No parking.
5. 动名词的复合结构作主语
当动名词有自己的逻辑主语时，常可以在前面加上一个名词或代词的所有格，构成动名词的复合结构(——这时，名词或代词的所有格做动名词的逻辑主语)。动名词的复合结构也可以在句中作主语。例如：
Their coming to help was a great encouragement to us.
6.例词
shopping fishing cycling这些都是很常见的动名词
二、动名词作主语与动词不定式作主语的比较
动词不定式和动名词都可以用作主语。在意义上相近。但动名词多用来表示泛指或抽象动作，不定式多用来表示特指或具体动作。比较：
Smoking is not good for health.
It is not good for you to smoke so much.
注意：
1)在口语中，用动名词作主语位于句首的较不定式多见。
2)在“It is no use...”，“It is no good...”，“It is fun...”，“It is a waste of time...”等句型中，通常用动名词作真实主语：
It is no use/good/a waste of time talking about that.
*It is no use/good/a waste of time to talk about that.
3)在疑问句中，通常用动名词的复合结构，而不用不定式的复合结构作主语：
Does your saying that mean anything to him?
*Does for you to say that mean anything to him?
4)在“There be”句型中，只能用动名词，而不能用不定式作主语：
There is no telling what will happen.
It is impossible to tell what will happen.
5)当句子中的主语和表语都是非限定动词时，要遵循前后一致的原则，主语和表语在形式上要求统一：
Seeing is believing.
*To see is to believe.
2、作宾语
（1）作动词的宾语
某些动词后出现非限定性动词时只能用动名词作宾语，不能用不定式。常见的此类动词有：advise, allow, permit, avoid, consider, enjoy, finish, give up, cannot help, imagine, include, keep, keep on, mind, miss, put off, delay, practise, resist, suggest, depend on, think about, set about, succeed in, worry about, burst out, insist on, can’t stand, be used to, get used to, devote…to…, look forward to, pay attention to, get down to等。如：
They went on walking and never stopped talking. 他们继续走，说个不停。
I found it pleasant walking along the seashore. 在海滩上走真是乐事。
（2）作介词的宾语
We are thinking of making a new plan for the next term. 我们正考虑为下学期制定新的计划。
Shall we have a rest or get down to doing our work? 我们休息呢还是开始干活？
（3）作形容词的宾语
The music is well worth listening to more than once. 这种曲子很值得多听几遍。
We are busy preparing for the coming sports meet. 我们正为马上到来的运动会忙着做准备。
3、作表语
动名词作表语时句子主语常是表示无生命的事物的名词或what引导的名词性从句。表语搜趣网动名词与主语通常是对等的关系，表示主语的内容，主语、表语可互换位置。
Your task is cleaning the windows. 你的任务就是擦窗户。(Cleaning the windows is your task.)
What I hate most is being laughed at. 我最痛恨的就是被别人嘲笑。 (Being laughed at is what I hate most.)
4、作定语
动名词作定语往往表示被修饰词的某种用途。如：
a walking stick ＝a stick for walking=a stick which is used for walking
a washing machine=a machine for eVIHuUwashing=a machine which is used for washing
a reading room=a room for reading=a room which is used for reading
a measuring tape=a tape for measuring=a tape which is used for measuring
sleeping pills=pills for sleeping=pills which is used for sleeping
二、动名词的逻辑主语
带有逻辑主语的动名词称为动名词的复合结构。当动名词的逻辑主语与句子的主语不一致时，要在动名词之前加上物主代词或名词所有格，这便构成了动名词的复合结构。其中物主代词（名词所有格）是逻辑上的主语，动名词是逻辑上的谓语。动名词复合结构在句中可作主语、宾语、表语等，分别相当于一个主语从句、宾语从句、表语从句。如：
Her coming to help encouraged all of us. 他来帮忙鼓舞了我。 (=That she came to help encouraged all of us.)
Jane’s being careless caused so much trouble. 简这么粗心惹来了不少麻烦。 (=That Jane was careless caused so much trouble.)
What’s troubling them is their not having enough food. 烦扰他们的是食物不足。 (=What’s troubling them is that they have not enough food.)
在口语中，如果动名词复合结构作宾语，其中的物主代词常用人称代词宾格，名词所有格常用名词普通格来代替，但在句首作主语时不能这样来代替。如：
Would you mind my/me using your computer? 用下你的电脑介意吗？
The father insisted on his son’s/his son going to college. 爸爸坚决要求儿子上大学。
Mary’s (不可用Mary) being ill made her mother upset. 玛丽病了，使她妈妈很着急。
His (不可用Him)smoking made his family angry. 他抽烟使他一家人非常生气。
在下列情况下动名词的逻辑主语必须用名词的普通格或人称代词宾语：
a.无命名词
The baby was made awake by the door suddenly shutting. 这个婴儿被猛烈的关门声吵醒。
b. 有生命名词但表示泛指意义
Have you ever heard of women practising boxing? 你听说过妇女练拳击吗？
c. 两个以上的有生命名词并列
Do you remember your parents and me telling about this? 你记得你父母和我都告诉过你这事吗？
三、动名词的时态和语态
动名词的时态和语态如下：
时态
主动语态
被动语态
一般式
writing
being written
完成式
having written
having been written
其否定形式是在doing前加上not
1、动名词一般式表示的动作通常是一般性动作，即不是明确地发生在过去、现在或将来的动作，或是与谓语动词所表示的动作同时发生的动作。如：
I hate talking with such people. 我讨厌与这样的人说话。
Being careless is not a good habit. 粗心不是一个好习惯。
2、动名词的完成式表示的动作发生在谓语动词动作之前。如：
I don’t remember having met him before. 我记不得以前见过他。
Thank you for having taking so much trouble to help. 谢谢你费力帮忙。
3、动名词的逻辑主语同时也是动名词动作的承受者，动名词用被动语态。
（1）它的一般式表示的动作与谓语动词动作同时发生，或在其前发生。如：
I don’t like being laughed at in public. 在公共场合下，我不喜欢被别人嘲笑。
（2）它的完成式表示的动作发生在谓语动词之前。如：
I am very pleased at your having been honoured with a medal. 我很高兴你能获得这样的奖牌。
（3）在某些动词，我们常用动名词的一般式表示完成式，尽管动作发生在谓语动词动作之前，这似乎是一种强大的习惯。如：
Excuse me for being late. 我来晚了请你原谅。
I don’t remember ever meeting somewhere. 我记不得原来在什么地方见过。
Thank you for giving us so much help. 谢谢给我们这么大的帮助。
（4）在多数情况下都避免使用动名词被动语态完成式，而用一般式代替，以免句子显得累赘，尤其是在口语中。如：
I forget once being taken (having been taken ) to the city zoo. 我曾被带到过这个动物园，可我忘了。
（5）动名词被动语态一般式与现在分词被动语态一般式同形，但无进行意义，being不可省略。如：
She is afraid of being taken to the public. 她怕被领到大众面前。
四、常见题型：
1） 动名词做主语时，谓语动词为单数
2） 在动名词和不定式中，作为介词的宾语是动名词
3） 动名词的否定直接在其前加否定词，通过代词的宾格或所有格形式给出逻辑主语
例：
I would appreciate_______ back this afternoon.
A．you to call B．you call C．you calling D．you’re calling（Key：C；换成your calling也对）
4） 有些词后只能接动名词
admit; appreciate; avoid; celebrate; consider; contemplate; defer; delay; deny; detest; discontinue; dislike; dispute; enjoy; it entails; escape; excuse; explain; fancy; feel like; finish; forgive; can’t help; hinder; imagine; it involves; keep; it means; mention; mind; miss; it necessitates; pardon; postpone; practice; prevent; recall; report; resent; resist; risk; suggest; understand...
5） 另外还有一些接-ing形式的常用说法
it’s no good; it’s no/little/hardly any/ use; it’s not/hardly/scarcely use; it’s worthwhile; spend money/time; there’s no; there’s no point in; there’s nothing worse than; what’s the use/point...
6） 有些词后面加不定式和动名词均可
remember, forget, try, stop, go on, cease, mean后面均可用不定式和-ing形式，但意义截然不容。
例：
remember to do/doing：
①I remembered to post the letters.（指未来/过去未来将要做的动作）
②I remembered posting/having posted the letters.（我记得做过这个动作）
forget与remember的用法类似。
regret的用法：
①I regret to inform you that…（我很遗憾地通知你……）
②I regretted having left the firm after twenty years.（为了“二十年前的离开”而遗憾。）
try to（努力）与try +–ing（试验）：
①You really must try to overcome your shyness.
②Try practicing five hours a day.
五、动名词与现在分词的同与不同
动名词它在形式上与现在分词相同，都是在动词原形的词末加-ing。在现代语法中，这两种形式同视为"-ing形式"。 这两种形式的另一个相同之处是：它们都是由动词变化而成的，它们都保留了动词的某些特征，它们都能带自己的宾语、状语，而构成动名词短语或是现在分词短语去担当句子成分。例如：
Speaking in the public , he will surely be very cheerful .
（现在分词短语，作状语）他在公众场所讲话时总是兴高采烈的。
She hates speaking in the public.
（动名词短语，作宾语）她不喜欢在公众场所讲话。
区别：
1､动名词和现在分词都可以用于系动词之后作表语,区别方法是:
①作表语的动名词与主语指的是同一件事,此时系动词相当于“是”,通常把主语和表语的位置互换,语法和意思不变,例如:
My hobby is swimming.可改为Swimming is my hobby.(可将原句中的主语与表语位置互换)
②现在分词作表语主要用以说明主语的性质,不能与主语互换位置,例如:
The story is interesting .不可改为:Interesting is the story.
2､动名词和现在分词都可以用作定语来修饰名词,两者的区别在于:
动名词修饰名词时主要表示该名词的用途,而现在分词修饰名词时性质､状态或动作等｡试比较:
①a swimming boy和a swimming suit
前者的意思是“一个正在游泳的男孩”,即a boy who is swimming ,现在分词swimming 表示被修饰名词boy的动作;而后者的意思是“游泳衣”,即a suit for swimming , 动名词swimming表示suit 的用途｡
②a sleeping child 和 a sleeping car
前者的意思是“一个正在睡觉的孩子”,即a child who is sleeping ,现在分词sleeping 表示被修饰名词 child 正处于的状态;而后者的意思是“卧车(被用来睡觉的车厢)”,即 a car which is used for sleeping ,动名词 sleeping 表示car 的用途｡
被动语态
一、 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.
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. 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.
4. 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.
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.
Your mistakes should be corrected right now.
The door may be locked inside.
Your homework can be handed in tomorrow.
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.
They are planting trees over there. →
Trees are being planted over there by them.
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.
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,或是间接宾语加被动语态再加只接宾语。
He gave me a book.→A book was given to me by him. 或是I was given a book by him.
He showed me a ticket.→A ticket was shown to me by him. 或是i was shown a ticket by him.
My father bought me a new bike. →A new bike was bought for me by my father. 或是Lwas bought a new bike 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 him. →He can’t be laugh 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.</CA>
英语语法
请问什么是主语从句，表语从句，定语从句，非谓语，同位语从句，不定式，非限定性定语从句？请解释清楚一点，最好有例句主语从句
一、概述：在句子中起名词作用的各种从句统称为名词性从句。根据它们在句中的语法作用，这类从句又可分为主语从句、同位语从句、表语从句和宾语从句。
二、 几个共性问题：
1．连接方式
（1） 在由连词that, whether, if引导的名词性从句中，引导词在句中不做成分，在宾语从句和表语从句中，that可以省略。
（2） 在由连接代词who, whose, whom, which, what, whoever, whomever, whichever, whatever引导的名词性从句中，其连接代词在句中起名词性作用，担当一定成分。
（3）在由连接副词when, where, why, how引导的名词性从句中，其连接副词在句中作状语。
2．whether和if的区别
（1）whether在引导的主语从句中可以置于句首，而if则不能。
（2）whether可以与or not连用，or not可以紧跟在whether之后，也可以置于从句末尾；if一般不能和or not连用。
（3）表语从句、同位语从句和介词宾语从句（即在系词be和介词之后），只能用whether连接，而不用if。
（4）从句是否定式时，一般用i//www.souquanme.comf, whether很少用在否定式从句中。
例如：I don’t care if he doesn’t come . 如果他不来，我也不介意。
The problem is whether we can carry out the plan.
问题是我们是否能实施这项计划。
三、 主语从句
1．主语从句主要有三类：
（1） 由连词that引导的主语从句。
例如：That you will win the medal seems unlikely.
你想获得奖牌看起来是不可能的。
That you are so indifferent bothers me.
你如此冷淡使我很烦恼。
That she survived the accident is a miracle.
她在事故中幸免于难简直是奇迹。
（2） 用连接代词或连接副词if, whether 引导的主语从句。
例如： Which of them escaped from the prison is still a mystery.
他们哪一个是从监狱里逃跑的，仍然是个谜。
When they will come hasn’t been made pubic.
他们什么时候来还不知道。
Whether she is coming or not doesn’t matter too much.
她来不来都无关紧要。
（3） 用关系代词引导的主语从句。
例如：What you need is more practice.
你所需要的是更多的训练。
What I want to know is this. 我想知道的就是这事。
Whatever we do is to serve the people.
我们无论做什么都是为人民服务。
主语从句可以直接放在主语位置上，也可以用it作形式主语，
而将从句放在句末（尤其是当谓语较短时）。
例如：That light travels in straight lines is known to all.
光沿直线传播，这是众所周知的事。
=It is known to all that light travels in straight lines.
众所周知光沿直线传播。
When the plane is to take off has not been announced .
飞机何时起飞还没有宣布。
= It has not been announced when the plane is to take off.
还没有宣布飞机何时起飞。
当what引导的主语从句表示“…的东西”时，一般不用it作形式主语。
错:It is a book what he wants.
对:What he wants is a book. 他想要的是本书。
如果带主语从句的句子是疑问式，则必须用it作形式主语的结构。
例如：Has it been settled who will be sent to carry out the task ?
谁将被派去执行这项任务决定了吗 ？
3．固定用法和译法
（1） It is +名词+从句
It is a fact that… 事实是……
It is good news that … ……是好消息
It is a question that … ……是个问题
It is common knowledge that … ……是常识
类似的名词还有：a pity；a wonder；a good thing； no wonder； surprise等。
例如：It is a mystery to me how it all happened.
这一切是怎么发生的是个谜。
It is common knowledge that the whale is not a fish.
鲸鱼不是鱼，这是常识。
It is no surprise that Bob should have won the game.
鲍勃会赢得这场比赛，这不足为奇。
（2） It is +形容词+从句
It is necessary that … 有必要……
It is clear that … 很清楚……
It is likely that … 很可能……
It is important that … 重要的是……
类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.
例如：It is obvious that conductors and insulators are both important in industry.
很明显导体和绝缘体在工业中都很重要。
It is doubtful whether she will be able to come.
她是否能来令人怀疑。
It was really astonishing that he refused to talk to you .
他拒绝和你说话真是令人惊讶。
It is essential that he should be here by the weekend .
周末之前，他应该到这里是必要的。
It seems obvious that we can not go on like this.
很明显我们不能这样下去了。
（3） It is +过去分词+从句
It is said that … 据说……
It is reported that … 据报道……
It has been proved that … 已证明……
It must be proved that… 必须指出……
类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc.
例如：It is thought that he is the best player.
大家都认为他是最好的选手。
It is estimated that the vase is 2000 years old.
据估计这个花瓶有2000年的历史。
It is used to be thought that a new star must be due to a collision between two stars. 过去一直认为新星是由于两颗星星之间碰撞产生的。
It has not been made clear when the new road is to be opened to traffic.
还没弄清楚这条路将开始通车。
（4） It +不及物动词+从句
It seems that … 好像是……
It happened that… 碰巧……
It follows that … 由此可见……
It has turned out that … 结果是……
类似的不及物动词还有：seem, appear, occur, follow, happen, turn out, etc.
例如：It turned out that nobody remembered the address.
结果是无人记得那个地址。
It now appears that they are in urgent need of help.
看起来他们急需帮助。
It does not matter if I missed my train, because there is another later.
没有赶上这趟火车没有关系，稍晚还有一趟。
It happened that I saw him yesterday.
碰巧我昨天看见他了。
当“及物动词 + 宾语”较短时，也可用这种结构。
例如：It shocked me that Peter did not tell anybody where he was.
让我吃惊的是彼得没有告诉任何人他在哪里。
It does not interest me whether you go or not.
我对你去不去不感兴趣。
It +某些固定结构+ 主语从句。
例如：It doesn’t make too much difference （It doesn’t make any difference / It doesn’t alter the situation），whether it rains or not . 下不下雨都没有多大关系。
It does not make any difference whether it rains or not .
下不下雨没什么分别。
It does not make the least difference to me what you do.
对我来说你做什么都无关紧要。
Is it of much consequence to you that Mr. Wang has failed to do it ? 王先生没有做成这件事对你有什么重要影响吗？
句子的表语是由一个句子充当的,那么这个充当表语的句子就叫做表语从句
The fact is that he was cheated.
这是个系表结构的句子,the fact是主语,谓语是系表结构,表语是that he was cheated,这个that引导的句子就是表语从句.
宾补和双宾的区别先看下面两个句子
They elected him president.
I sent him a telegram.
第一个句子里面的him是elect的宾语,而president则不是elect的宾语,它是补充说明宾语him的情况.
第二个句子里面的him 依然是send的宾语,而telegram也是send的宾语
定语从句（Attributive Clauses）在句中做定语，修饰一个名词或代词，被修饰的名词，词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。
非谓语动词主要包括不定式、动名词和现在分词。为了区分这三种不同的非谓语动词的用法和含义，我们将分别从三种非谓语动词在句子中做主语、宾语、宾语补足语、定语、状语、
表语以及一些特殊结构句型等角度来区分其用法和细微含义。
1．不定式和动名词作主语的区别
(1)动名词作主语通常表示抽象动作；而不定式作主语表示具体动作。
Smoking is prohibited(禁止)here．这里禁止抽烟。(抽象)
It is not very good for you to smoke so much．你抽这么多烟对你身体很不好。(具体)
(2)动名词作主语时，通常用以表示一件已知的事或经验。
不定式短语通常用来表示一件未完成的事或目的。
Climbing mountains is interesting．爬山很有趣。(经验)
Driving a car during the rush hour is tiring．在高峰时刻开车令人厌烦。(经验)
（3）不定式做主语，一般用it当形式主语，把作主语的不定式短语后置。
It took me only five minutes to finish the job.
2．不定式、动名词和分词作表语的区别
(1)不定式作表语
1)不定式作表语一般表示具体动作，特别是表示将来的动作。
To do two things at a time is to do neither．--次做两件事等于未做。
What I would suggest is to start work at once.我的建议是立刻开始干。
2）如果主语是不定式（表示条件），表语也是不定式（表示结果）。
To see is to believe.百闻不如一见
To work means to earn a living．工作就是为了生活。
3)如果主语是以aim，duty，hope，idea，happiness，job，plan，problem，purpose，thing，wish等为中心的名词，或以what引导的名词性从句，不定式作表语是对主语起补充说明作用。
His wish is to buy a luxurious car in the near future．他的希望是在不远的将来买一辆豪华轿车。
The function of Louis Sullivan’s architecture was to provide large uninterrupted floor areas and to allow ample light into the interior.
The most important thing is to negotiate with them about the future of the plant．
(2)动名词作表语：动名词作表语，表示抽象的一般性的行为。
Our work is serving the people．我们的工作是为人民服务。
His hobby is collecting stamps．他的爱好是集邮。
(注)动名词作表语时与进行时态中的现在分词形式相同，但其所属结构迥异，进行时态说明动作是由主语完成的。动名词做表语，说明主语的性质或情况。
People cannot but feel puzzled，for they simply cannot understand how he could have made such a stupid mistake.
His victory in the final was no more convincing than I had expected．
(3)分词作表语
分词做表语有两种情况，一种是现在分词做表语，一种是过去分词做表语，这两者区别是考试中经常考到的地方。一般来说，表示心理状态的动词如excite，interest等都是及物动词，汉语意思不是“激动”，“高兴”，而是“使激动”、“使高兴”，因而现在分词应该是“令人激动的”、“令人高兴的”，过去分词则是“感到激动的”和“感到高兴的”。所以，凡表示“令人……的”都是-ing形式，凡是表示“感到……”都用-ed形式。换句话说，若人对……感兴趣，就是somebody is interested in...,若人/物本身有兴趣时，就是说sb./sth. is interesting.这类词常见的有：
interesting使人感到高兴--interested感到高兴的
exciting令人激动的--excited感到激动的
delighting令人高兴的--delighted感到高兴的
disappointing令人失望的--disappointed感到失望的
encouraging令人鼓舞的--encouraged感到鼓舞的
pleasing令人愉快的--pleased感到愉快的
puzzling令人费解的--puzzled感到费解的
satisfying令人满意的---satisfied感到满意的
surprising令人惊异的--surprised感到惊异的
worrying令人担心的--worried感到担心的
Travelling is interesting but tiring．旅行是有趣的，但是使人疲劳。
The pupils will get confused if they are made to learn too much．如果要学生学得太多，他们会感到糊涂的。
The argument is very convincing．他的论点很令人信服。
They were very excited at the news．听到这个消息，他们非常激动。
3．不定式和动名词作宾语的区别
英语中大多数动词既可跟不定式，也可跟动名词作直接宾语，但有些动词要求：
(1)不定式做宾语和宾语补足语
1)下面的动词要求不定式做宾语
attempt企图 enable能够 neglect忽视
afford负担得起 demand要求 long渴望
arrange安排 destine注定 mean意欲，打算
begin开始 expect期望 omit忽略，漏
appear似乎，显得 determine决定 manage设法
cease停止 hate憎恨，厌恶 pretend假装
ask问 dread害怕 need需要
agree同意
同位语从句用于对前面的名词作进一步解释，说明名词的具体内容。同位语从句一般由that引导，但也可以由whether 以及连接代词和连接副词引导。
同位语从句一般跟在名词fact, hope, idea, news, doubt, suggestion, information, opinion, decision, discovery, truth, promise, statement, problem, rule等的面。
They were all very much worried over the fact that you were sick. 对你生病这件事，他们都很焦虑。
Where did you get the idea that I could not come 你在哪儿听说我不能来？
I have no idea whether he'll come or not. 我不知道他是否来。
在一些表示建议、命令、要求的名词后的同位语从句中，谓语动词用should+动词原形表示，should可省略。
This is our only request that this (hould) be settled as soon as possible. 尽快解决这个问题，这是我们唯一的请求。
He made the suggestion that we go by train. 他建议我们坐火车去。
不定式是英语动词的一种形式。它在许多情况下可省略"to"它不同于汉语动词，汉语动词只有一种形式。如：我看书。她看书。但英语要说“看”必须根据主语的人称，动作发生的时间等确定其形式。如：1）I read a book. 2）She reads a book.1）句中的“read”
是一般现在时第一人称的动词定式。2）句中的“reads”是一般现在时第三人称单数的动词定式。
I want to read a book./She wants to read a book.
我想要看书。她想要看书。其中的“看”不易确定其形式。因为动作还未发生，因此称不定式。通俗的说，就是“不一定是什么形式”
请看例句： I want to go. 我想去
在这个句子中有两个动词，want 和 to go
want 是这个句子的主要动词，它随着主语的人称、数和时态而变化，如：He wants to go. We wanted to go.
to go 不管主语的数、人称和时态如何变化，它永远保持“to + 动词原型”的形式，to go 就是不定式。
动词不定式的基本形式是to + 动词原型，有时可以不带to, 动词不定式没有人称和数的变化，在句子中不能作谓语。
动词不定式仍保留动词的特点，即它可以有自己的宾语和状语。动词不定式和它的宾语或状语构成不定式短语。如：
I want to read the book. 我想读这本书。
book 是 read 的宾语，to read the book 为不定式短语。
1) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开，例如：
This is the house which we bought last month. 这是我们上个月买的那幢房子。（限制性）
The house, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买的。（非限制性）
2) 当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句通常是非限制性的，例如：
Charles Smith, who was my former teacher, retired last year. 查理史密斯去年退休了，他曾经是我的老师。
My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。
This novel, which I have read three times, is very touching. 这本小说很动人，我已经读了三遍。
3) 非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这时从句谓语动词要用第三人称单数，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎没抓住我的意思，这使我心烦。
Liquid water changes to vapor, which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。
一、概述：在句子中起名词作用的各种从句统称为名词性从句。根据它们在句中的语法作用，这类从句又可分为主语从句、同位语从句、表语从句和宾语从句。
二、 几个共性问题：
1．连接方式
（1） 在由连词that, whether, if引导的名词性从句中，引导词在句中不做成分，在宾语从句和表语从句中，that可以省略。
（2） 在由连接代词who, whose, whom, which, what, whoever, whomever, whichever, whatever引导的名词性从句中，其连接代词在句中起名词性作用，担当一定成分。
（3）在由连接副词when, where, why, how引导的名词性从句中，其连接副词在句中作状语。
2．whether和if的区别
（1）whether在引导的主语从句中可以置于句首，而if则不能。
（2）whether可以与or not连用，or not可以紧跟在whether之后，也可以置于从句末尾；if一般不能和or not连用。
（3）表语从句、同位语从句和介词宾语从句（即在系词be和介词之后），只能用whether连接，而不用if。
（4）从句是否定式时，一般用i//www.souquanme.comf, whether很少用在否定式从句中。
例如：I don’t care if he doesn’t come . 如果他不来，我也不介意。
The problem is whether we can carry out the plan.
问题是我们是否能实施这项计划。
三、 主语从句
1．主语从句主要有三类：
（1） 由连词that引导的主语从句。
例如：That you will win the medal seems unlikely.
你想获得奖牌看起来是不可能的。
That you are so indifferent bothers me.
你如此冷淡使我很烦恼。
That she survived the accident is a miracle.
她在事故中幸免于难简直是奇迹。
（2） 用连接代词或连接副词if, whether 引导的主语从句。
例如： Which of them escaped from the prison is still a mystery.
他们哪一个是从监狱里逃跑的，仍然是个谜。
When they will come hasn’t been made pubic.
他们什么时候来还不知道。
Whether she is coming or not doesn’t matter too much.
她来不来都无关紧要。
（3） 用关系代词引导的主语从句。
例如：What you need is more practice.
你所需要的是更多的训练。
What I want to know is this. 我想知道的就是这事。
Whatever we do is to serve the people.
我们无论做什么都是为人民服务。
主语从句可以直接放在主语位置上，也可以用it作形式主语，
而将从句放在句末（尤其是当谓语较短时）。
例如：That light travels in straight lines is known to all.
光沿直线传播，这是众所周知的事。
=It is known to all that light travels in straight lines.
众所周知光沿直线传播。
When the plane is to take off has not been announced .
飞机何时起飞还没有宣布。
= It has not been announced when the plane is to take off.
还没有宣布飞机何时起飞。
当what引导的主语从句表示“…的东西”时，一般不用it作形式主语。
错:It is a book what he wants.
对:What he wants is a book. 他想要的是本书。
如果带主语从句的句子是疑问式，则必须用it作形式主语的结构。
例如：Has it been settled who will be sent to carry out the task ?
谁将被派去执行这项任务决定了吗 ？
3．固定用法和译法
（1） It is +名词+从句
It is a fact that… 事实是……
It is good news that … ……是好消息
It is a question that … ……是个问题
It is common knowledge that … ……是常识
类似的名词还有：a pity；a wonder；a good thing； no wonder； surprise等。
例如：It is a mystery to me how it all happened.
这一切是怎么发生的是个谜。
It is common knowledge that the whale is not a fish.
鲸鱼不是鱼，这是常识。
It is no surprise that Bob should have won the game.
鲍勃会赢得这场比赛，这不足为奇。
（2） It is +形容词+从句
It is necessary that … 有必要……
It is clear that … 很清楚……
It is likely that … 很可能……
It is important that … 重要的是……
类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.
例如：It is obvious that conductors and insulators are both important in industry.
很明显导体和绝缘体在工业中都很重要。
It is doubtful whether she will be able to come.
她是否能来令人怀疑。
It was really astonishing that he refused to talk to you .
他拒绝和你说话真是令人惊讶。
It is essential that he should be here by the weekend .
周末之前，他应该到这里是必要的。
It seems obvious that we can not go on like this.
很明显我们不能这样下去了。
（3） It is +过去分词+从句
It is said that … 据说……
It is reported that … 据报道……
It has been proved that … 已证明……
It must be proved that… 必须指出……
类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc.
例如：It is thought that he is the best player.
大家都认为他是最好的选手。
It is estimated that the vase is 2000 years old.
据估计这个花瓶有2000年的历史。
It is used to be thought that a new star must be due to a collision between two stars. 过去一直认为新星是由于两颗星星之间碰撞产生的。
It has not been made clear when the new road is to be opened to traffic.
还没弄清楚这条路将开始通车。
（4） It +不及物动词+从句
It seems that … 好像是……
It happened that… 碰巧……
It follows that … 由此可见……
It has turned out that … 结果是……
类似的不及物动词还有：seem, appear, occur, follow, happen, turn out, etc.
例如：It turned out that nobody remembered the address.
结果是无人记得那个地址。
It now appears that they are in urgent need of help.
看起来他们急需帮助。
It does not matter if I missed my train, because there is another later.
没有赶上这趟火车没有关系，稍晚还有一趟。
It happened that I saw him yesterday.
碰巧我昨天看见他了。
当“及物动词 + 宾语”较短时，也可用这种结构。
例如：It shocked me that Peter did not tell anybody where he was.
让我吃惊的是彼得没有告诉任何人他在哪里。
It does not interest me whether you go or not.
我对你去不去不感兴趣。
It +某些固定结构+ 主语从句。
例如：It doesn’t make too much difference （It doesn’t make any difference / It doesn’t alter the situation），whether it rains or not . 下不下雨都没有多大关系。
It does not make any difference whether it rains or not .
下不下雨没什么分别。
It does not make the least difference to me what you do.
对我来说你做什么都无关紧要。
Is it of much consequence to you that Mr. Wang has failed to do it ? 王先生没有做成这件事对你有什么重要影响吗？
句子的表语是由一个句子充当的,那么这个充当表语的句子就叫做表语从句
The fact is that he was cheated.
这是个系表结构的句子,the fact是主语,谓语是系表结构,表语是that he was cheated,这个that引导的句子就是表语从句.
宾补和双宾的区别先看下面两个句子
They elected him president.
I sent him a telegram.
第一个句子里面的him是elect的宾语,而president则不是elect的宾语,它是补充说明宾语him的情况.
第二个句子里面的him 依然是send的宾语,而telegram也是send的宾语
定语从句（Attributive Clauses）在句中做定语，修饰一个名词或代词，被修饰的名词，词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。
非谓语动词主要包括不定式、动名词和现在分词。为了区分这三种不同的非谓语动词的用法和含义，我们将分别从三种非谓语动词在句子中做主语、宾语、宾语补足语、定语、状语、
表语以及一些特殊结构句型等角度来区分其用法和细微含义。
1．不定式和动名词作主语的区别
(1)动名词作主语通常表示抽象动作；而不定式作主语表示具体动作。
Smoking is prohibited(禁止)here．这里禁止抽烟。(抽象)
It is not very good for you to smoke so much．你抽这么多烟对你身体很不好。(具体)
(2)动名词作主语时，通常用以表示一件已知的事或经验。
不定式短语通常用来表示一件未完成的事或目的。
Climbing mountains is interesting．爬山很有趣。(经验)
Driving a car during the rush hour is tiring．在高峰时刻开车令人厌烦。(经验)
（3）不定式做主语，一般用it当形式主语，把作主语的不定式短语后置。
It took me only five minutes to finish the job.
2．不定式、动名词和分词作表语的区别
(1)不定式作表语
1)不定式作表语一般表示具体动作，特别是表示将来的动作。
To do two things at a time is to do neither．--次做两件事等于未做。
What I would suggest is to start work at once.我的建议是立刻开始干。
2）如果主语是不定式（表示条件），表语也是不定式（表示结果）。
To see is to believe.百闻不如一见
To work means to earn a living．工作就是为了生活。
3)如果主语是以aim，duty，hope，idea，happiness，job，plan，problem，purpose，thing，wish等为中心的名词，或以what引导的名词性从句，不定式作表语是对主语起补充说明作用。
His wish is to buy a luxurious car in the near future．他的希望是在不远的将来买一辆豪华轿车。
The function of Louis Sullivan’s architecture was to provide large uninterrupted floor areas and to allow ample light into the interior.
The most important thing is to negotiate with them about the future of the plant．
(2)动名词作表语：动名词作表语，表示抽象的一般性的行为。
Our work is serving the people．我们的工作是为人民服务。
His hobby is collecting stamps．他的爱好是集邮。
(注)动名词作表语时与进行时态中的现在分词形式相同，但其所属结构迥异，进行时态说明动作是由主语完成的。动名词做表语，说明主语的性质或情况。
People cannot but feel puzzled，for they simply cannot understand how he could have made such a stupid mistake.
His victory in the final was no more convincing than I had expected．
(3)分词作表语
分词做表语有两种情况，一种是现在分词做表语，一种是过去分词做表语，这两者区别是考试中经常考到的地方。一般来说，表示心理状态的动词如excite，interest等都是及物动词，汉语意思不是“激动”，“高兴”，而是“使激动”、“使高兴”，因而现在分词应该是“令人激动的”、“令人高兴的”，过去分词则是“感到激动的”和“感到高兴的”。所以，凡表示“令人……的”都是-ing形式，凡是表示“感到……”都用-ed形式。换句话说，若人对……感兴趣，就是somebody is interested in...,若人/物本身有兴趣时，就是说sb./sth. is interesting.这类词常见的有：
interesting使人感到高兴--interested感到高兴的
exciting令人激动的--excited感到激动的
delighting令人高兴的--delighted感到高兴的
disappointing令人失望的--disappointed感到失望的
encouraging令人鼓舞的--encouraged感到鼓舞的
pleasing令人愉快的--pleased感到愉快的
puzzling令人费解的--puzzled感到费解的
satisfying令人满意的---satisfied感到满意的
surprising令人惊异的--surprised感到惊异的
worrying令人担心的--worried感到担心的
Travelling is interesting but tiring．旅行是有趣的，但是使人疲劳。
The pupils will get confused if they are made to learn too much．如果要学生学得太多，他们会感到糊涂的。
The argument is very convincing．他的论点很令人信服。
They were very excited at the news．听到这个消息，他们非常激动。
3．不定式和动名词作宾语的区别
英语中大多数动词既可跟不定式，也可跟动名词作直接宾语，但有些动词要求：
(1)不定式做宾语和宾语补足语
1)下面的动词要求不定式做宾语
attempt企图 enable能够 neglect忽视
afford负担得起 demand要求 long渴望
arrange安排 destine注定 mean意欲，打算
begin开始 expect期望 omit忽略，漏
appear似乎，显得 determine决定 manage设法
cease停止 hate憎恨，厌恶 pretend假装
ask问 dread害怕 need需要
agree同意
同位语从句用于对前面的名词作进一步解释，说明名词的具体内容。同位语从句一般由that引导，但也可以由whether 以及连接代词和连接副词引导。
同位语从句一般跟在名词fact, hope, idea, news, doubt, suggestion, information, opinion, decision, discovery, truth, promise, statement, problem, rule等的面。
They were all very much worried over the fact that you were sick. 对你生病这件事，他们都很焦虑。
Where did you get the idea that I could not come 你在哪儿听说我不能来？
I have no idea whether he'll come or not. 我不知道他是否来。
在一些表示建议、命令、要求的名词后的同位语从句中，谓语动词用should+动词原形表示，should可省略。
This is our only request that this (hould) be settled as soon as possible. 尽快解决这个问题，这是我们唯一的请求。
He made the suggestion that we go by train. 他建议我们坐火车去。
不定式是英语动词的一种形式。它在许多情况下可省略"to"它不同于汉语动词，汉语动词只有一种形式。如：我看书。她看书。但英语要说“看”必须根据主语的人称，动作发生的时间等确定其形式。如：1）I read a book. 2）She reads a book.1）句中的“read”
是一般现在时第一人称的动词定式。2）句中的“reads”是一般现在时第三人称单数的动词定式。
I want to read a book./She wants to read a book.
我想要看书。她想要看书。其中的“看”不易确定其形式。因为动作还未发生，因此称不定式。通俗的说，就是“不一定是什么形式”
请看例句： I want to go. 我想去
在这个句子中有两个动词，want 和 to go
want 是这个句子的主要动词，它随着主语的人称、数和时态而变化，如：He wants to go. We wanted to go.
to go 不管主语的数、人称和时态如何变化，它永远保持“to + 动词原型”的形式，to go 就是不定式。
动词不定式的基本形式是to + 动词原型，有时可以不带to, 动词不定式没有人称和数的变化，在句子中不能作谓语。
动词不定式仍保留动词的特点，即它可以有自己的宾语和状语。动词不定式和它的宾语或状语构成不定式短语。如：
I want to read the book. 我想读这本书。
book 是 read 的宾语，to read the book 为不定式短语。
1) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开，例如：
This is the house which we bought last month. 这是我们上个月买的那幢房子。（限制性）
The house, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买的。（非限制性）
2) 当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句通常是非限制性的，例如：
Charles Smith, who was my former teacher, retired last year. 查理史密斯去年退休了，他曾经是我的老师。
My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。
This novel, which I have read three times, is very touching. 这本小说很动人，我已经读了三遍。
3) 非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这时从句谓语动词要用第三人称单数，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎没抓住我的意思，这使我心烦。
Liquid water changes to vapor, which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。
高二英语
1、when we climbed up the mountains ,my legs were so weak that i could ___stand.faily almost nearly hardly2、This is the reason __he gave us for being late for the meeting.先行词 reason的引导词怎么选，是固定的吗?3、Last month,southeast Asia was struck by floods ,from __effects the peopleare still suffering.that whose those what还有floods可数的？1、hardly，本义是“艰难地，困难地”，一般实用化地翻译成“几乎不”，也就是“难到几乎不能”。句中的意思是：爬山途中，双腿乏力以至于几乎站都站不起。给出的4个词中，只有hardly才有“困难到不行”的“近似否定”意味。也就是说，hardly本身不是否定词，而是在意思是类似于否定词。
2、此处空白可填that/which或补填。因为该处先行词作的gave的宾语（直接宾语，指事情），因为是宾语所以可以省略，其它情况下均不能省略。
关于reason的先行词究竟选哪个要看语境：如果跟该句一样作宾语，则that/which/补填都行，如果是主语从句或同位语从句，习惯上用that，如果是表语从句还可以用why，例如: This is the reason why he was late for the meeting.（这个表语从句也可以理解成reason的后置定语从句，只不过它作表语reason的定语而已）
3、选whose。记住一条：定语从句中，无聊对象是人还是物，对应的“形容词”性质的先行词都是whose。因为英语中经常“人/事/物”同用。
至于floods一词时不时可数的，就如同waters和airs等词一样，是老外用出来的，严格地说flood跟water都是不可数的，但老外经常混着用，这时候floods一般指“大面积的洪水，一大片的洪水”，说白了是把“可数名词”的用法借用或移用到“不可数名词”上。这是用法的问题，不是单词词义本身的问题。
2、此处空白可填that/which或补填。因为该处先行词作的gave的宾语（直接宾语，指事情），因为是宾语所以可以省略，其它情况下均不能省略。
关于reason的先行词究竟选哪个要看语境：如果跟该句一样作宾语，则that/which/补填都行，如果是主语从句或同位语从句，习惯上用that，如果是表语从句还可以用why，例如: This is the reason why he was late for the meeting.（这个表语从句也可以理解成reason的后置定语从句，只不过它作表语reason的定语而已）
3、选whose。记住一条：定语从句中，无聊对象是人还是物，对应的“形容词”性质的先行词都是whose。因为英语中经常“人/事/物”同用。
至于floods一词时不时可数的，就如同waters和airs等词一样，是老外用出来的，严格地说flood跟water都是不可数的，但老外经常混着用，这时候floods一般指“大面积的洪水，一大片的洪水”，说白了是把“可数名词”的用法借用或移用到“不可数名词”上。这是用法的问题，不是单词词义本身的问题。
帮忙做一下这道题 ！！！！
He hurt his leg climbing the mountain;otherwise,he____the meeting. A will attend B had attend C would have attended D would attend答案是C
本题考查了虚拟语气的用法，关键词是otherwise
题意是“他爬山的时，腿受伤了。否则，他会去开会的”，也就是说“如果他的腿没有受伤，他会去开会”。而事实上，他腿受伤了，他也没去开会。和过去的事实相反。
句子可以改写为：If he hadn't huret his leg climbing the mountain, he would have attended the meeting.
另附虚拟语气用法：
1)在虚拟语气的从句中，动词'be'的过去时态一律用"were"，不用was， 即在从句中be用were代替。
If I were you, I would go to look for him. 如果我是你，就会去找他。
2)用 if you were me
What would you do if you were me? 如果你是我，你会怎么做?
3）was主要用在It‘s time结构中，在该用was的时候不能用were
eg It’ time I was in bed 。 我该上床睡觉了。（这里不能用were）
4）一些用法 ：
a. 同现在事实相反的假设。
句型 ： 条件从句 主句
一般过去时 should( would) +动词原形
If they were here, they would help you.
b. 表示于过去事实相反的假设。
句型： 条件从句 主句
过去完成时 should(would) have+ 过去分词
If she had worked harder, she would have succeeded.
c. 表示对将来的假想
句型： 条件从句 主句
一般过去时 should+ 动词原形
were+ 不定式 would + 动词原形
should+ 动词原形
If you succeeded, everything would be all right.
d It is (high) time that
It is (high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
It is time that the children went to bed.
It is high time that the children should go to bed.
e It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形， should 可省略。
其他还有一些小语法 这里就不一一列举了。
希望能帮到你！
本题考查了虚拟语气的用法，关键词是otherwise
题意是“他爬山的时，腿受伤了。否则，他会去开会的”，也就是说“如果他的腿没有受伤，他会去开会”。而事实上，他腿受伤了，他也没去开会。和过去的事实相反。
句子可以改写为：If he hadn't huret his leg climbing the mountain, he would have attended the meeting.
另附虚拟语气用法：
1)在虚拟语气的从句中，动词'be'的过去时态一律用"were"，不用was， 即在从句中be用were代替。
If I were you, I would go to look for him. 如果我是你，就会去找他。
2)用 if you were me
What would you do if you were me? 如果你是我，你会怎么做?
3）was主要用在It‘s time结构中，在该用was的时候不能用were
eg It’ time I was in bed 。 我该上床睡觉了。（这里不能用were）
4）一些用法 ：
a. 同现在事实相反的假设。
句型 ： 条件从句 主句
一般过去时 should( would) +动词原形
If they were here, they would help you.
b. 表示于过去事实相反的假设。
句型： 条件从句 主句
过去完成时 should(would) have+ 过去分词
If she had worked harder, she would have succeeded.
c. 表示对将来的假想
句型： 条件从句 主句
一般过去时 should+ 动词原形
were+ 不定式 would + 动词原形
should+ 动词原形
If you succeeded, everything would be all right.
d It is (high) time that
It is (high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
It is time that the children went to bed.
It is high time that the children should go to bed.
e It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形， should 可省略。
其他还有一些小语法 这里就不一一列举了。
希望能帮到你！
