英语中as, for, so, while等连词的用法

英语连词的用法
As
一．As 用作连词的用法：
1. as用作连词引导时间状语从句
①as与when，while都是引导时间状语从句的从属连词，含义都是"当……的时候"。

但它们有区别：用when时，从句的动作可以与主句的动作同时发生，也可以先于主句的动作发生；用while时，从句的动作为一过程，主句动作与从句动作同时进行或在从句动作过程中发生；用as时，主句和从句的动作同时发生，具有延续的含义。

例如：
(1)It was snowing when he arrived at the construction site.他到达工地时，天正在下雪。

(2)He was watching TV while his mother was cooking.他母亲做饭时他在看电视。

(3) You will grow wiser as you grow older.你会随着年龄的增长而越来越聪明。

②when作"当……的时候"解,可以指较短的(一点)时间,也可指一段时间。

如:
When he was at college, he could speak several foreign languages.
When the clock struck twelve, all the lights in the street went out.
③while常表示一段较长的时间或一个过程,强调主句谓语动词与从句谓语动词同时发生。

如:
Work while you work. Play while you play.
④但属下列情形时,只用as, 而不用when或while。

A) 用于表示同一个人的两种动作交替进行,指"一边……,一边……"。

如:
The girl dances as she sings on the stage.
He looked behind from time to time as he went forward.
B)表示两个同步发展的动作或行为,译为"随着……"。

如:
As time went on / by, she became more and more worried.
As children get older, they become more and more interested in the things around them.
C)表示两个短促行为或动作几乎同时发生。

如:
I thought of it just as you opened your mouth.
Just as the flying worm hit her face, she g*e a loud cry.
D) 后接名词表示某一年龄段时,用as。

如:
As a young man, he was active in sports.
2. as用作连词引导原因状语从句
①as，because，since都可以表示因果关系，连接原因状语从句，含义是"因为，由于"，但它们有区别：because表示的语气最强；as一般放在句首，语气较弱，较口语化；since 常常用在书面语中，表示多为对方已知的、或稍加分析便可得知的原因。

例如：
(1) He will succeed because he is in earnest.他一定会成功，因为他很认真。

(2) Since you are so sure of it he’ll believe you.既然你对此如此有把握，他会相信你的。

(3) As rain has fallen, the air is cooler.因为下过雨，空气比较清爽。

②as=since, 作"既然"、"由于"解,引导原因状语从句,常用来表示已为人们所知或显而易见的原因或理由。

如:
As / Since you're not feeling well, you may stay at dangerour place.
As/Since he wasn't ready in time, we went without him.
3. as作连词引导让步状语从句
as与although (或though)，however (或no matter how)等都可以引导让步状语从句，含义是"虽然，尽管"，但它们有区别：although语气稍正式些，可放在句首，也可放在句中，主句中不能再用but，但可以用yet；as所表示的语气较强，引导的让步状语从句用倒装语序,即adj. /adv. / n.+ as +主语+谓语+主句；however引导让步状语从句时，它的后面可跟形容词或副词，也要用倒装语序。

例如：
(1) Although he is quite old, he still jogs every day.他虽然年纪相当大，仍然每天慢跑。

(2) Strange as it may seem, nobody was injured in the accident.这次意外虽然显得令人不可思议，却没有人受伤。

Tired as they were, they walked on.
Child as he is, he knows a lot. (child前不用冠词)
(3) However hard he may try, he will not attain his goal.无论他怎样努力也达不到目标。

4.As作连词引导方式状语从句
As=in the way that, 作"像"、"按照……的方式"解,引导方式状语从句。

如:
He speaks English as Americans do.
Remember, you must do everything as I do.
5. as...as的用法
as...as意为"和……一样"，表示同级的比较。

使用时要注意第一个as为副词，第二个as为连词。

其基本结构为：as+ adj./ adv. +as。

例如：
(1)This film is as interesting as that one.这部电影和那部电影一样有趣。

(2)Your pen writes as smoothly as mine.你的钢笔书写起来和我的一样流畅。

其否定式为not as/so +adj./ adv. +as。

例如：
This dictionary is not as/so useful as you think.这本字典不如你想象的那样有用。

若有修饰成分，如twice, three times, half, a quarter等，则须置于第一个as之前。

例如：
Your bag is twice as expensive as mine.你的袋子比我的贵一倍。

用于as...as...或not so/ as...as...中,引导比较状语从句。

如:
They helped the old man as often as possible.
I don't speak English so/ as well as he does.
几个关于as...as的常见句型：
(1)as...as possible
Please answer my question as soon as possible.请尽快回答我的问题。

(2)as...as usual/before
She looks as pretty as before.她看起来和以前一样漂亮。

(3)as long as... (引导条件状语从句)
It took us as long as three years to carry out the plan.我们花了长达三年的时间才完成这项计划。

(4)as far as
He walked as far as the railway station yesterday evening.昨天傍晚，他一直散步到火车站。

(5)as well as
She cooks as well as her mother does.她烧菜烧得跟她母亲一样好。

一些带有as...as结构的常见短语归纳：
as busy as a bee像蜜蜂一样忙碌
as easy as ABC像ABC一样容易
as deep as a well像井一样深
as light as a feather像羽毛一样轻
as soft as butter像黄油一样软
as rich as a Jew像犹太人一样富裕
二、as作关系代词的用法
关系代词as引导定语从句时，既可以单独使用，也可以与其他词连用，其用法要比that 和which更为复杂。

1. as引导定语从句与其他词连用
①用于the same...as结构中
This is the same book as I read last week.这本书和我上周读的那本是一样的。

I was reading the same book as he bought yesterday.
②用于such...as结构中
I don’t like such books as he recommends.我不喜欢他推荐的那些书。

Such a clever boy as he can learn anything quickly.
③用于"so +adj. + a/an + n. (单数) + as "结构中
I am not so strong a man as I was.我已经没有从前那么强壮了。

2. as单独引导定语从句
①as单独引导定语从句时，先行词可以是一个词，也可以是一个句子或短语。

例如：
(1) She is late, as is often the case.她迟到了，这是经常的事。

(先行词是整个主句)
(2) To shut your eyes to facts, as many of you do, is foolish.对事实视而不见---你们好多人都是如此的愚蠢。

(先行词是不定式短语)
②as作关系代词,引导定语从句,作"正如"、"这一点"解。

如:
He is very careful, as his work shows.
As is well-known, Taiwan belongs to China.
As is known to everybody, the moon travels round the earth once every month.
三、as作介词的用法
①as作介词，意思是"作为"，"以……身份"。

例如：
He came to China as a tourist five years ago.他五年前以游客的身份来过中国。

As a League member, I'll take the lead in everything. (状语)
She works as a doctor. (状语)
②少数情况可引起宾语补足语。

如:
They have me as one of their own children.(引起宾语补足语)
四、as作副词的用法
to the same degree or amount; equally "相同地"，"同样地"。

例如：
They don’t h ave as many airplanes.他们没有同样多的飞机。

For
用法1：(表目的)为了。

如：
They went out for a walk. 他们出去散步了。

What did you do that for? 你干吗这样做？
That’s what we’re here for. 这正是我们来的目的。

What’s she gone for this time? 她这次去干什么去了？
He was waiting for the bus. 他在等公共汽车。

【用法说明】
通常，英语不用 for doing sth 来表示目的。

如：
他去那儿看他叔叔。

误：He went there for seeing his uncle.
正：He went there to see his uncle.
但是，若一个动名词已名词化，则可与 for 连用表目的。

如：
He went there for swimming. 他去那儿游泳。

(swimming 已名词化)
注意：若不是表目的，而是表原因、用途等，则其后可接动名词。

(见下面的有关用法) 用法2：(表利益)为，为了。

如：
What can I do for you? 你想要我什么？
We study hard for our motherland. 我们为祖国努力学习。

Would you please carry this for me? 请你替我提这个东西好吗？
Do more exercise for the good of your health. 为了健康你要多运动。

【用法说明】
(1) 有些后接双宾语的动词(如 buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通常用 for 来引出间接宾语，表示间接宾语为受益者。

如：
She made her daughter a dress. / She made a dress for her daughter. 她为她女儿做了件连衣裙。

He cooked us some potatoes. / He cooked some potatoes for us. 他为我们煮了些土豆。

注意，类似下面这样的句子必须用 for：
He bought a new chair for the office. 他为办公室买了张新办公椅。

(2) 注意不要按汉语字面意思，在一些及物动词后误加介词 for：
他们决定在电视上为他们的新产品打广告。

误：They decided to advertise for their new product on TV.
正：They decided to advertise their new product on TV.
注：advertise 可用作及物或不及物动词，但含义不同：advertise sth＝为卖出某物而打广告；advertise for sth＝为寻找某物而打广告。

如：advertise for a job=登广告求职。

由于受汉语“为”的影响，而此处误加了介词 for。

类似地，汉语中的“为人民服务”，说成英语是 serve the people，而不是 serve for the people，“为某人的死报仇”，说成英语是avenge sb’s death，而不是avenge for sb’s death，等等。

用法3：(表用途)用于，用来。

如：
Knives are used for cutting things. 小刀是用来切东西的。

This knife is for cutting bread. 这把小刀是用于切面包的。

It’s a machine for slicing bread. 这是切面包的机器。

The doctor gave her some medicine for her cold. 医生给了她一些感冒药。

用法4：为得到，为拿到，为取得。

如：
He went home for his book. 他回家拿书。

He went to his friend for advice. 他去向朋友请教。

She often asked her parents for money. 她经常向父母要钱。

We all hope for success. 我们都盼望成功。

Are you coming in for some tea? 你要不要进来喝点茶？
用法5：给(某人)，供(某人)用。

如：
That’s for you. 这是给你的。

Here is a letter for you. 这是你的信。

Have you room for me there? 你那边能给我腾出点地方吗？
用法6：(表原因、理由)因为，由于。

如：
I am sorry for it. 对不起。

Thank you for coming to see me. 谢谢你来看我。

You can’t see the wood for the trees. 你只见树木，不见森林。

He is famous for his poems. 他因为他的诗出名。

He was sent to prison for robbery. 他因为抢劫而坐牢。

I couldn’t speak for laughing. 我笑得说不出话来。

He couldn’t sleep for joy. 他高兴得不能入睡。

For several reasons, I’d rather not meet her. 由于种种原因，我宁愿不见她。

【用法说明】有些表原因的特殊结构不宜用介词 for 来引出，而用其他介词。

如：他由于努力工作而加了工资。

误：For the result of his hard work, he got a pay rise.
正：As a [the] result of his hard work, he got a pay rise.
注：as a [the] result of 是习语，意为“由于……的结果”。

因为母亲不在家，她只好自己做饭。

误：For Mother (being) away, she had to cook the meal herself.
正：With Mother (being) away, she had to cook the meal herself.
注：“with+宾语+宾语补足语”可用来表示原因，此时的 with 不能换成 for。

类似地，下例中的 with 也不能换成 for：
With all this work to do, I don’t know if I’ll have time to go out. 有这么多工作要做，我不知是否有时间出去。

我们祝贺你的成功。

误：We congratulate you for your success.
正：We congratulate you on your success.
注：congratulate 后习惯上接介词 on 表示原因。

用法7：(表目标、去向)去。

如：
Is this bus for Chicago? 这辆公共汽车开往芝加哥吗？
They’ll leave for Beijing tomorrow. 明天他们动身去北京。

They set off for the shops. 他们买东西去了。

Is this the train for Shanghai? 这是开往上海的火车吗？
Passengers for Tianjing must change at Beijing. 去天津的旅客必须在北京换车。

【用法说明】比较 for 与 to，两者均可表示目的地，注意以下区别：
for 通常与 leave, start, set out, set off, head, steer, depart, be bound, be destined 等动词连用，而 to 则通常与 come, drive, fly, get, go, lead, march, move, return, ride, run, travel, walk 等动词连用。

如：
We departed for London at 10 am. 我们上午10点动身去伦敦。

Then we drove to the station. 然后我们就开车去了车站。

有时，同一个动词(如 sail)两者均可连用，但含义稍有差别：用 for 通常只表示向着某目的地那个方向，并不强调到达的意思；而 to 含有到达某目的地的意思。

如：They sailed for Shanghai. 他们开船驶往广州。

They sailed to Shanghai. 他们开船驶至广州。

若与名词连用，也有类似区别。

如：
There will be a train for Wuhan. 有开往武汉的火车。

(仅表示向武汉方向，但在武汉未必是停靠站)
There will be a train to Wuhan. 有开往武汉的火车。

(开往武汉方向，且在武汉停靠)
顺便说一句，也有的辞书持几乎相反的观点，认为 for 与 to 表示目的地时，for 表示的是预定目的地，而to 表示的是假设将会到达的目的地。

用法8：(表时间、距离、数量等)达，计。

如：
I’m going away for a few days. 我要走开几天。

I’ve been here for ten years. 我来这儿有10年了。

He walked for ten miles. 他走了10英里路。

The shop sent me a bill for $50. 商店给我送来了一张50美元的账单。

【用法说明】for 用于表示时间或距离的长度(尤其是紧跟在动词之后)时，有时可省略。

如：
The meeting lasted (for) three days. 会议持续了3天。

They walked (for) fifty miles. 他们走了50英里。

但是当 for 短语位于句首或在否定句中时, for 通常不宜省去。

如：
For ten years he lived here. 他在这里住过10年。

We have not heard from him for a long time. 我们很久没收到他的来信了。

用法9：对，对于。

如：
Eggs are good for you. 鸡蛋对你有好处。

Reading in bed is bad for your eyes. 躺在床上看书对你的眼睛不好。

Fortunately for me, the train was also late. 我很走运，火车也晚点了。

【用法说明】关于 for 与 to 表示“对……来说”时的区别，参见 to。

用法10：(表适合)适于，适合。

如：
Do you have any books for children? 你有适合小孩子看的书吗？
He is the very person for the work. 他是最适合做这工作的人。

It’s a good place for a camp. 那是个露营的好地方。

She bought some clothes for winter. 她买了些冬天穿的衣服。

用法11：(表交换)换，以……作交换。

如：
He gave her some magazines for her dictionary. 他用几本杂志换她的字典。

She bought the skirt for $50. 她花了50美元买这条裙子。

I bought a pound of apples for 70 cents. 我花了七角钱买了一磅苹果。

Don’t translate word for word. 不要逐字硬译。

用法12：作为，当作。

如：
Don’t take him for a fool. 别把他当傻瓜。

He mistook a rope for a snake. 他把一条绳子误认为是蛇。

He knew that for a fact. 他知道那是事实。

The missing persons were given up for dead. 大家都认为那些失踪的人已死了。

【用法说明】用于此义时，有时相当于 as, to be, as being，但要注意不同句型的搭配习惯。

如：
I took him for an honest man. / I took him to be honest. 我看他为人老实。

It was built for [as] a pleasure boat. 这船建作游艇之用。

比较：
He took her smile for agreement. 他把她的微笑视为同意。

Will you take me as your partner? 你把我看作你的合伙人好吗？
按传统语法，take…for… 通常指误认为是……，而take…as [to be] 则主要指正确地认为是……。

但在现代英语中，有时并未完全遵守此规则。

但是与 mistake 连用的则通常是 for 而不是 as。

如：
We mistook the house for a hotel. 我们把那房子误以为旅馆。

用法13：(表支持、赞成)支持，赞成。

如：
Are you for or against the plan？你是支持还是反对这个计划？
I’m all for the young enjoying themselves. 我完全赞成年轻人多玩玩。

用法14：(表基准)就……来说，以……而言，作为。

如：
He’s done well for a beginner. 作为新手，他干得很好。

He is heavy for a small boy. 作为一个小男孩而言，他的身体算重的了。

She was short for her age. 就她的年龄来说，个子是矮了点。

The day is cool for July. 在7月里这样的日子算是凉快的了。

用法15：(表比例)每……就……。

如： Plant three trees for every one that is cut down. 每砍一棵树要种三棵树。

He has one enemy for a hundred friends. 他的敌人与朋友之比为一比一百。

For every five who passed, there were two who failed. 每5个人及格，就有2个不及格。

For every mistake you make, you’ll lose half a mark. 你每犯一个错误，就要扣去半分。

【用法说明】用于此义时，通常与 each, every 或数词连用。

用法16：代表，代替，代理。

如：
What’s the English for “中国”? 英语里“中国”怎么说？
What’s the “C” for in “BBC”? BBC中的C代表什么？
Red is for danger. 红色代表危险。

Let me do it for you. 让我替你做吧。

The lawyer acted for him during the trial. 在审案期间由律师代表他行事。

用法17：(表安排的时间)在，于。

如：
The appointment is for 10:30. 约会定在十点半。

We’ve invited our guests for 7 o’clock. 我们已邀请我们的客人7点钟来。

We’ve booked our holiday for the second week in July. 我们的假期安排在七月份的第二个星期。

The next meeting was arranged for the tenth of May. 下次会议已定于5月10日举行。

【用法说明】用于此义时，for 主要指安排或约定的时间，所以像下面两例中的介词at，in 就不能换成 for。

如：
He gets up at six every day. 他每天6点钟起床。

He was born in September, 1988. 他出生于1988年9月。

用法18：(表让步)尽管，虽然。

如：
For all his money, he’s a very lonely man. 他虽然富有，可是非常寂寞。

For all his efforts, he didn’t succeed. 尽管他做了很多努力，却仍然没有成功。

I love you, for all your shortcomings. 尽管你有很多缺点，但我仍然爱你。

【用法说明】用于此义时，通常与 all 连用。

用法19：与不定式连用引出逻辑上的主语。

如：
It is for you to decide. 该由你来决定。

All I want is for us to be together. 我希望的只是我们能在一起。

Is there any need for me to go? 我有没有必要去？
He spoke too fast for her to follow. 他说得太快，她跟不上。

It is a great pity for him to leave here so soon. 他这么快就离开这里真是遗憾。

It is dangerous for a small child to cross the road alone. 小孩子自己过马路很危险。

For a bridge to collapse like that is unbelievable. 一座桥像那样倒塌是不可想像的。

【用法说明】
(1) 下面两句同义，但以第一句为普通。

如：
老人快跑是危险的。

正：It is dangerous for an old man to run fast.
正：For an old man to run fast is dangerous.
(2) 有时可表目的。

如：
I’ve sent my coat away for it to be cleaned. 我把外衣送去洗了。

For sales to increase, we must lower our prices. 为了增加销量，我们必须降低价格。

(3) 有时用于 than 后引出不定式的逻辑主语。

如：
There’s nothing worse than for a person to ill-treat a child. 没有什么比
虐待小孩更恶劣的了。

链接for的用法
1．表示\"当作、作为\"。

如：I\'d like some bread and milk for breakfast.
2．表示动作的对象或接受者，意为\"就......而言\"、\"对......来说\"。

如：It\'s important for us to learn English well. Art is fun for someone.
3．表示理由或原因，意为\"因为、由于\"。

如： Thank you for teaching us so well.
4．表示对象、用途，意为\"为\"、\"适于\"。

如：Li Ming and Wang Mei are looking at their photos for the class picture.
5．表示去向、目标，意为\"向、往、取、买\"等。

如：I came here for my schoolbag.
6．表示时间、距离，意为\"计、达\"。

如：She has been an English teacher for seven years.
7．表示与具体条件作比较，意为\"比起来\"、\"就......来看\"。

如：It\'s rather hot for May.
TO
一：表示相对，针对如：be strange (common, new, familiar, peculiar, distinct, sensitive, immune, vulnerable, indispensable) to
Air is indispensable to life.
Aircrafts are vulnerable to interference caused by radiation.
This injection will make you immune to infection.
二：表示对比，比较
1：以-ior结尾的形容词，后接介词to表示比较，如：superior , inferior, prior, senior, junior
The quarrel happened prior to my arrival.
2:一些本身就含有比较或比拟意思的形容词，如:equal，similar，equivalent，analogous
A is similar to
B in many ways.
3：表示一些先后顺序的形容词，如：
econd,subsequent,next,preliminary,preparatory
Subsequent to the war,they returned to their hometown.
4:to也偶尔出现在个别动词之后,与动词形成固定词组,表示比较,如:prefer
to,compare to,in contrast to compare to sth.表示比喻或比拟,而compare with sth.
表示比较,如:
World is usually compared to a stage
Compared with his past,he has changed a lot.
Prefer的正确句型是:prefer A to B或prefer doing A to doing B,但当prefer后接动词不定式时,表示比较的介词to就要改成rather than ,如:
The undaunted soldier preferred death to surrender.
Many people prefer spending money to earning money.
They prefer to pursue careers rather than remain home as house wives.
5:to与及个别的名词构成比较之意,如:alternative
Going to an under water concert is a great alternative to going to dinner.
三:表示修饰关系
1:表示回复,反应意思的词,如:answer to question, solution to problem,response to inquiry,reaction to proposal,reply to letter
2:表示建筑构件的词汇,如: entry, entrance, approach, access, passage, exit, vent, path
the approach to a bridge
the approach to science
Half of the population was estimated to have no access to the health service.
The access to education 接受教育的机会
The access to medical care 享受公费医疗的权利
4:表示人物职位和官衔的词,如:assistant to manager, ambassador to Spain, successor to tradition, heir to throne,deputy to the National People’s Congress, advisor to the Prime Minister
5:表示权利和许可的词汇,如:right,admission
The employee finally got the admission to the boardroom.
Every one has an equal right to ……..
6:表示栅栏或障碍的词汇,如:bars to development,the barrier to progress
7:表示与书籍,文本相关的词,如:introduction to passage.
8:表示恭喜或是祝贺,如:
The director proposed a toast to the health of the guests.
Let’s drink to Dick’s success in busi ness
9:另外还有一些名词符合这种用法,有的具有两者息息相关,缺一不可的含义.如:key to door,invitation to party, guide to action,limitation to life,accessory to school 四:to还具有依据,伴随,和着节奏的含义如:sing to piano, chance to the tune, stamp to the rhythm of the song, add salt to taste
五：表示相关联，相连接如：be related to,be relative to,in relation to,be relevant to,link to
Investigate all the facts related to the problem.
People often linked walth to happiness.
六：表示反对和赞同。

1：to引导的表示反对，抗拒，对抗意义的词组。

如：Be opposed to,be oppsist to,be contrary to,be adverse to,be resistant to,be contradictory to,object to,oppose to,deny tp,be aline to
These buildings are resistant to earthquake.
They are to tally opposed to any changes being made in the plans.
2:to引导的表示同意，赞同意义的词组。

如：consent to,subseribe to
The employer consented to give him a salary raise.
3:表示调整，使符合，使适应的含义，如：adapt to,commodate to,adjust to,conform to,habituate to,fit to,suit to,correspond to,cater to
She tried to habituate herself to the style of plain living.
Your action should conform to the interests of the people.
They offered various foods to cater to the need of customers.
His words doesn’t fit to his actions.
Suit your writing style to the masses.
4:表示投降,屈服,服从的含义,如:be subject to,be subordinate to,submit
to,subject to,surrender to,give in to,confess to,admit to.
The minority is subordinate to the majority少数服从多数
Countries nearby oceans are always subject to earthquake.
He confessed to having robbed the woman of her wallet.
We’re not the kind of people to yield to any military threat.
七:表示趋势或倾向如:tend to,be prone to,be inclined to,be apt to,be liable to
He’s liable to seasickness.
You are liable to come to wrong conclusion.
八:表示对事情的坚持与执着,如:sick to,hold o,adhere to,cling to
He still holds on to his original views.
九:表示约束,局限,如:limit to,confine to,resrict to
He’s confined to the house by illness.
He confined his remarks to scientific mangement.
十:表示一种习惯或是一种适应性,如:get (be) to,used to,be accustomed to Finally,the students got used to my teaching method.
十一:表示起因和原由,如:owing to,due to,thanks to,attribute to,come down to The flight was cancelled due to the thick fog.
The famous artist attributed his success to his wife.
十二:表示命运,注定,如:be doomed to,be destined to,
All military adventures by the two super powers are doomed to fail.
十三:表示数量上的积累或增加,如:in addition to,add to,amount to
In addition to relief supplies,he also presented with some money.
The annual output of steel amounts to 1200 tons.
十四:表示全身心投入的含义,如:be addicted to,contribute to,devote to,commit to
He is determined to devote all his life to his.
十五:表示展望或是回顾,如:look forward to 反date back to
The church dates back to the 13th century.
十六:表示方位概念.如:close to,next to
I don’t like wool next to my skin.
十七:表示依靠或借助,如:resort to,turn to,appeal to,
He usually appeals to arms to settle the territory dispute.
十八:表示有关注,关于如:as to,with regard to
十九:表示关注或重视,如:pay attention to,attach to,
We should attach primary importance to job training.
二十:表示依据或是根据,如:according to,in proportion to
According to today’s newspaper,the match will be postponed.
The lending countries subscribe towards capital stock in proportion to their economic importance.
二十一:表示应该或必须含义的句式,如:
It’s time to get up.
We are supposed to get here at seven.
It’s up to this country to ban nuclear weapons.
二十二:表示目的或结果,如:aim to,lead to,give rise to
I aim to be an excellent college teacher.
His conceit lead to his failure.
These bad condition has given rise to a lot of crises
常用词组
respond to（反应）,appeal to（吸引）,catch on to（理解）,listen to（收听）,used to（过去常常）,give birth to,attend to（照料）,see to（负责）,be entitled to（有权）,belong to（属于）,come to（苏醒）,stand up to（勇敢面对）,help oneself to （请自便）,refer to,to the point（切题）,
Train them to stand up to any severe test in hard.
The ticket entitled you to a free meal in the luxury hotel.
See to it that the children get a hot meal after their swim.
You will catch on to the job shortly after wards.
People usually refer to television for up-to-the-minute news.
OF
1:表示剥夺,除去
一:deprive ***. of his right
denude ***. of his possession (hope)
divest the baby of his clothes
rid him of this fear
rob ***. of his wallet
defraud ***. of gold ring
cure ***. of cancer
heal ***. of cancer
purify the nation clean the jar of crust
clarify the river of flowing rubbish
--get rid of, rid of, dispose of
2:of接直接宾语
-告诉-tell ***. of sth. inform ***. of sth warn ***. of fire
remind ***. of his duties acquaint ***. of sth. notify of..
-其他,劝服-persuade ***. of honesty assure ***. of the best seats convince ***. of sth.
-法律词汇-accuse ***. of burglary ; convict ***. of murder; suspect ***. of a theft
-reassure his wife of his safe arrival
3:of接间接宾语
request sth. of ***. expect sth. of ***. require sth. of ***. ask a question of ***. be fearful of mistakes be jealous of wealthy persons be reminiscent of his past be patient of the enormous noise be guilty of robbery be innocent of robbery 4:of表示人物的特性,籍贯,特性或出生等
He is of Irish descend (ascent)
People of obscure origin (humble /noble)
Man of keen perception a man of moral integrity
5:固定词组
-say of, tale of, hear of, think of, learn of, savor of
The room smells of stale cabbage.
-brag of his achievements. Boast of his children
beware of pickpockets approve of the program
doubt of success complain of poor management
-be sure of be suspicious of be aware of
be confident of be proud of be ashamed of
be afraid of be capable of be lack of
be critical of be shortly of be conscious of
be ignorant of be wary of be cautious og
be appreciative of your advice
-regardless of , irrespective of ,不管….无视
in favor of
decide on three most popular leisure
activities irrespective of age
链接of的用法
1．表示\"属于关系\"，意为\"（属于）......的\"。

如：the leaves of the tree 2．表示\"（关于）......的\"。

如：stories of Lei Feng, a map of China
3．表示\"同位关系\"。

如：He lives in the city of Beijing.
4．表示某人的品性。

如：It\'s very kind of you to help me.
5．表示\"因为、由于\"。

如：die of cancer（死于癌症）
6．用于一些固定短语中。

如：Shirts and blouses are made of cotton. I have a lot of homework today.
7．表示整体与部分的关系。

如：three or four of your classmates，the end of the film（这部电影的片末部分）
IF
一、if作为连词，引导条件状语从句。

它表示的意思是“假如”“如果”等。

在复合句中如果主句用将来时，则if引导的状语从句用一般现在时。

例如：
1. If itdoesn’train, we will go to the park next Sunday. 如果天不下雨，下周星期天我们将去公园。

2. If you ask him，he will help you．如果你求他，他将会帮助你。

二、if还可以引导让步状语从句。

这时if当作“即使是”，“虽说”解。

例如：
1. If she’s poor，at least she’s honest．虽说她很穷，但至少她还是诚实的。

2. If I am wrong，you are wrong， too．即使说我错了，那么你也不对。

3. I’ll do it, even if it takes me all the afternoon．虽然会花费我一下午的时间，我还是要做这事。

三、if作为连词还可以引导宾语从句。

引导宾语从句时和whether意思相同。

例如：
1. Lily asked if ／ whether she liked it. 莉莉问她是否喜欢它。

2. She asked if ／ whether they had a cotton one．她问是否他们有一件棉织的。

四、if引导时间状语从句。

当if做“当”或“无论何时”解而不含有条件之义时，if 从句中的时态与主句中的时态相同。

例如：
1. If youmix yellow and blue，you get green．你将黄色与蓝色混合，便会得到绿色。