非谓语动词句首辨析

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.

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)attempt企图 enable能够 neglect忽视等要求不定式做宾语
2)ask要求,邀请 get请,得到 prompt促使等要求不定式做宾补:动词+宾语+动词不定式
(2)有少数动词只能用动名词作宾语
例如:I appreciate having been given the opportunity to study abroad two years ago.我很感激两年前给我出国学习的机会。

(3)有些动词后使用动名词和动词不定式作宾语的差别

1)forget to do 忘记要去做某事(此事未做)
forget doing忘记做过某事(此事已做过或已发生)
2)stop to do 停止、中断(某件事),目的是去做另一件事
stop doing 停止正在或经常做的事,等等

4.不定式、现在分词和过去分词作定语的区别

(1)不定式作定语

1)不定式与其所修饰的名词可能是主谓关系
He was the last one to leave school yesterday.昨天他是最后一个离开教室的。
The train to arrive was from London.将要到站的火车是从伦敦开来的。

2)不定式与其所修饰的名词可能是动宾关系
Get him something to eat.给他拿点儿东西吃。
She has a lot of work to do in the morning.早上他有很多工作要做。

3)不及物动词构成的不定式做定语,要加上适当的介词和被修饰的名词形成逻辑上的动宾关系,这里的介词不能省去。
I need a pen to write with.我需要一支笔写字。
There is nothing to worry about.没有什么值得发愁的。

4)不定式修饰一些表示方向、原因、时间、机会、权利等抽象名词如:
ability能力,本领 drive赶,驾驶 movement运动,活动

5)被修饰的名词前有序数词、形容词最高级或next, second, last, only和not a,the等限定词时候,只能用不定式。

6)不定代词something, nothing, little, much, a lot 等习惯上用不定式做定语。
John will do anything but work on a farm.除了农活,约翰什么都愿意干。

7)如果其动词要求用不定式做宾语,或者其形容词要器接不定式做补语,则相应的名词一般用不定式做定语。如: tend to do—tendency to do;decide to do = decision to do;be curious to do = curiosity to do
His wish to buy a car came true.他要买辆车的愿望实现了。

(2)分词作定语

分词作定语时有下面几个特点:
1)现在分词表示主动意义,过去分词一般表示被动含意。

2)现在分词表示正在进行,过去分词表示状态或做完(完成)的事。

He rushed into the burning house.他冲进了正在燃烧着的房子。

3)下列不及物动词也以过去分词形式做定语或表语,但不具有被动意义,这点要注意:
departed, elapsed, faded, fallen, gone, frown-up, retired, returned, risen, set, vanished, much-traveled, newly-arrived, recently-come

(3)不定式和分词作定语时的时间关系

一般来说,不定式所表示的动作发生在谓语动词所表示的动作之后;现在分词所表示的动作与谓语动词所表示的动作同时发生;过去分词表示的动作发生在谓语动词所表示的动作之前。例如:
Do you want to see the doctor to be sent for from Beijing?
你要见那位将从北京请来的医生吗?
Do you want to see the doctor working on the case report in the office?
你要见那位正在办公室里写病历的医生吗?

5.不定式和分词作状语的区别

(1)现在分词与过去分词作状语的区别。

现在分词做状语与过去分词做状语的最主要区别在于两者与所修饰的主语的主动与被动关系的区别。

1)现在分词作状语时,现在分词的动作就是句子主语的动作,它们之间的关系是主动关系。
He went out shutting the door behind him.
他出去后将门随手关上。
Not knowing what to do, he went to his parents for help.
由于不知如何办是好,他去找父母帮忙。

2)过去分词作状语时,过去分词表示的动作是句子主语承受的动作,它们之间的关系是被动关系。
Given more attention, the trees could have grown better.
如果对这些树多关心一些,它们本来会长得更好。
Faced with difficulties, we must try to overcome them.
在遇到困难的时候,我们必须设法克服。

(2)动词不定式和分词作状语的区别

1)分词作状语一般表示伴随,而不定式常常表示目的。
They stood by the roadside talking about the plan.他们站在路边谈论着这个计划。(伴随)
They stood by the roadside to talk about the plan.他们站在路边为的是谈论这个计划。(目的)

2)分词作状语放在句子开头,除表示原因之外有时表示时间或条件。动词不定式作状语时,除了表示目的以外,还表示结果或原因。
Reading attentively,he forgot the time for lunch.由于在专心读书,他忘了吃午饭的时间。(原因)
Reading carefully,he found something he had not known before.他仔细读书时,发现了一些从前不知道的东西。(时间)
Reading carefully,you’ll learn something new.只要你仔细阅读,你会学到一些新的东西。(条件)
His family was too poor to support him.他的家庭太穷,不能维持他的生活。(结果)
The boy is not tall enough to reach the book shelf.这男孩个子不够高,手伸不到书架。(结果)
We are glad to hear the news.我们很高兴听到这消息。(原因)

(3)下面一些句型是不定式做状语时候应该注意的:
a:not/never too…to, too…not to , but/only too… to, too ready/eager/apt/inclined to 表示肯定意义
b:做结果状语的不定式只能出现在句子的末尾,常见的不定式动词有:find, hear, see, be told, form, give, make, produce 等。
c:不定式做状语时,其逻辑主语一般为句子的主语,否则用for引导主语。

6.非谓语动词常考的其它结构

(1)疑问词+不定式结构

疑问词who,what,which,when,where和how后加不定式可构成一种特殊的不定式短语。它在句中可以用作主语、宾语、表语和双重宾语。如:
When to start has not been decided.何时动身尚未决定。(主语)
I don’t know what to do.我不知道该怎么办。(宾语)
The difficulty was how to cross the river.困难在于如何过河。(表语)
I can tell you where to get this book.我可以告诉你哪里可以买到此书。(双重宾语)
注)A.有时疑问词前可用介词,如:
I have no idea of how to do it.我不知道如何做此事。
B.动词know 后面不能直接跟不定式作宾语,只能跟疑问词(如:how, what)+不定式:
While still a young boy, Tom knew to play the piano well and as he grew older, he wrote operas, the most famous of which is Carmen.

(2)介词except和but作“只有…,只能…”讲时跟不定式结构(but与不带to的不定式连用)。
When the streets are full of melting snow, you cannot help but getting your shoes wet.

(3)不带to的不定式
1)在表示生理感觉的动词后的不定式不带to。这类词有:
feel 觉得 observe 注意到,看到 overhear听到
watch注视 listen to听 perceive察觉,感知
notice注意 see看见 look at看 hear听
On seeing the young child fell into the lake,Eric sprang to his feet,and went on the rescue.

2)另一类是某些使役动词,如make, let,have等。如:
Let him do it.让他做吧。
I would have you know that I am ill.我想要你知道我病了。
(注):
①上述感觉动词与使役动词转换为被动结构时.其后的不定式一般需带to,如:
He was seen to come.
The boy was made to go to bed early.
②在动词find与help之后,不定式可带to亦可不带to,如:
He was surprised to find the sheep (to) break fence at this season.他发现羊在此季节越出栅栏,感到惊讶。

3)在do nothing/anything/everything but(except)结构中。例如:
Last night I did nothing but watch TV.昨天晚上,我除了看电视别的什么也没有干。
但是,如果谓语动词不是“do nothing,anything,everything”,那么but(except)所跟的不定式则仍须带。
The doctor told him nothing but to stop smoking.医生除了让他戒烟,其它什么都没有说。
There was nothing for them to do but to remain silent.除了保持沉默以外,他们没有别有别的办法。

(4)不定式与动名词的逻辑主语和分词独立结构
1)不定式的逻辑主语为:for +名词(或代词宾格)+ 不定式。例如:
I found it impossible for him to do the job alone.我发现他—个人干这活是不可能的。
(注)在表示人物性格、特性等的形容词后面,常用of引出不定式的逻辑主语。例如:
It was wise of him to do that.他那样做是明智的。
2)动名词的逻辑主语为;①人称代词的所有格+动名词;②名词’s+动名词。例如:
Tom insisted on my going with them.他坚持要我和他们一起去。
He dislikes his wife’s working late.他不喜欢他妻子工作得很晚。
3)某些形容词,如:careless等不定式后可以加of来引导出其逻辑主语。这类词主要有:absurd, bold, brave, courageous, careful, careless, clever, wise, foolish, silly, stupid, good, nice, kind thoughtful, considerate, greedy, generous, honest, modest, polite, rude, cruel ,selfish, wicked, wrong等
It is very kind of you to help me.你帮助我太好了。
间或也可用for + there to be表示(而且there后面的不定式只能是to be)。
It’s a great pity for there to be much trouble in the company.太遗憾了公司里有这么多的麻烦