问个非谓语动词的问题请问我怎么能确定一个在谓语动词后面的非谓语动词是用不定式还是用动名词?

Question

问个非谓语动词的问题
请问我怎么能确定一个在谓语动词后面的非谓语动词是用不定式还是用动名词?

Answer 1

非谓语动词是指动词在句中不独立作谓语时采用的形式,包括不定式、动名词和分词（现在分词、过去分词）三种.
不定式
1 不定式的形式
动词不定式的基本形式是“to＋动词原形”,称为带to的不定式；有时,to可以省略,称为不带to的不定式.例如：
He wanted to sit down. 他想坐下.（带to的不定式）
Let him sit down. 让他坐下. （不带to的不定式）
这里的to只是个语法符号,没有词义.不定式在句中不能独立作谓语,也没有人称和数的变化.但是,不定式作为动词的一种形式,依然保留了动词的特点,即可以有自己的宾语、状语等,有时,还可以有某种时态的变化（如完成时形式）.不定式与其附属部分一起构成不定式短语,在句中充当一定的句子成分.例如：to learn English, to work hard, to have waited a long time等等.
2 不定式的基本用法
动词不定式虽然是动词的一种形式,但是它却具有名词、形容词和副词的功能,因此在句中可以用作主语、表语、宾语、宾语补足语（宾补）、定语、状语等.
⑴ 用作主语：不定式作主语常位于句末,而在其原来的位置用it作形式主语.例如：
To learn a foreign language is not easy.
It is not easy to learn a foreign language.
学习一门外语并不容易.
To help the poor is his duty.
It is his duty to help the poor.
帮助穷人是他的责任.
⑵ 用作表语：不定式可以用在连系动词后作表语.例如：
To see is to believe. 眼见为实.
His wish is to become a pianist. 他的愿望是当一名钢琴家.
To the doctor, the most important thing is to save lives. 对于医生来说,最重要的就是挽救人的生命.
⑶ 用作宾语：不定式在部分单宾及物动词后用作宾语,这类动词常用的有：agree, begin, choose, dare, decide, expect, forget, hate, hope, learn, like, love, need, offer, prefer, promise, refuse, remember, start, try, want, wish, would like等等.例如：
I hope to see her soon. 我希望很快见到她.
She wants to go to university some day. 她想有朝一日去上大学.
He began to read and write after lunch. 午饭后,他开始读书写字.（当一个以上的不定式连用时,后面的不定式往往省略to.）
We found it impossible to cross the river. 我们发现无法过河.（本句中的it是形式宾语,不定式短语to cross the river是真正的宾语.）
⑷ 用作宾语补足语：不定式作宾语补足语时有两种情况：
① 在大多数复宾及物动词后,要用带to的不定式,这类及物动词常用的有：allow, ask, beg, enable, encourage, expect, find, get, hate, help, invite, like, order, prefer, tell, wait for, want, warn, wish, would like等等.例如：
They asked him to sing a pop song at the party. 他们请他在晚会上唱了一首流行歌曲.
She wants her brother to go to university. 她想要他的兄弟去上大学.
We are waiting for the doctor to come. 我们正在等医生来.
② 在表示五官感觉、致使等意义的动词后,要用不带to的不定式,这类动词有：feel, hear, notice, see, watch; have, let, make等.help有时也可用不带to的不定式.例如：
They heard him sing a song in the meeting room. 他们听见他在会议室唱了一首歌.
The boy saw two men enter the house. 那个孩子看见两个人进了那座房子.
The young man made the old machine start working. 那个年轻人使那台旧机器开动了.
The teachers helped the students (to) learn English well. 老师帮助学生学好英语.
本类动词在变成被动语态时,原句中作宾补的不定式前要加上to,同时原来的宾补就变成了主语补足语.例如：
Two men were seen to enter the house. 有人看见两个人进了那座房子.
The old machine was made to start working by the young man. 那台旧机器被那个年轻人开动了.
⑸ 用作定语：不定式可以像形容词一样用来修饰名词,但是它必须后置.例如：
He is always the first (person) to come to the office. 他总是第一个到办公室（的人）.
The teacher will have something important to tell us. 老师将会有重要的事情告诉我们.
He is not a man to talk with. 他不是一个可以与之交谈的人.（本句末尾的介词with不可遗忘.）
We must first find something for him to eat. 我们必须先给他找点吃的来.（本句中的for him为不定式to eat的逻辑主语.）
⑹ 用作状语：不定式用作状语时一定要带to,可以表示多种语义,如目的、结果、程度、原因等.
① 用作目的状语,例如：
He came to borrow my dictionary. 他是来借我的词典的.
They went on foot, so as not to be heard.
In order not to be heard, they went on foot.
他们步行前往,以免被人听见.
so as to, in order to意思都是“以便,为的是”,它们都可以用在句中,但是在句首要用in order to.另外,以上后两句例句中用了否定式,意思是“以免,免得”.
② 用作结果状语,例如：
He hurried to the house, only to find it empty. 他匆忙赶到那屋子,发现已经空无一人.
She left home, never to return again. 她离开了家再也没有回来.
He was so foolish as to leave his car unlocked. 他是那样傻,竟然没锁车.
③ 用作程度状语,例如：
She is old enough to travel all by herself. 她已经到了可以独自旅行的年龄了.
She is too young to swim across the big river. 她年纪太小,不能游过这条大河.
④ 用作原因状语,例如：
We jumped with joy to hear the news. 听到这消息我们高兴得跳了起来.
She wept to find them deep in debt. 她因发现他们负债累累而流泪.
I am very pleased to meet you. 我很高兴见到你.
3 不定式使用中的几个问题
⑴ 不定式前可以带what, when等疑问词（why除外）,构成“疑问词＋to do”短语,可以用作主语、表语、宾语等成分.例如：
How to get there is a question. 怎样去那里是一个问题.（主语）
The problem is which to choose. 问题是选择哪一个.（表语）
He didn’t tell us when to set out. 他没有告诉我们何时动身.（宾语）
⑵ 不定式的否定形式是在符号to的前面加否定词not,例如：
The head of the group told them not to stay too long. 队长吩咐他们不要在那里呆太久.
We’ve decided not to buy the house there. 我们决定不买那里的房子.
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分词
1 分词的形式
分词有现在分词和过去分词两种.现在分词由“动词原形＋-ing”构成（如：ask → asking, study → studying, live → living, stop → stopping）.现在分词短语具有形容词和副词的作用,在句中可用作多种句子成分.过去分词的构成有两种：规则的变化由“动词原形＋-ed”构成（如：ask → asked, live → lived, study → studied, stop → stopped）,不规则的变化请参见教材中的《不规则动词表》.
2 分词的基本用法
⑴ 用作定语：如果是单词,则为前置定语,现在分词表示正在进行的行为,过去分词表示性质或行为所造成的结果状态；如果是短语,则为后置定语,其作用相当于定语从句,现在分词表示一个正在进行的主动行为,过去分词则表示被动的行为.例如：
a sleeping boy = a boy who is sleeping 一个正在睡觉的孩子
the rising sun = the sun that is rising 正在升起的太阳
He is a young man with pleasing manner. 他是一个举止讨人喜欢的年轻人.
The room was full of people waiting for the headmaster. 房间里挤满了等候校长的人们.
We need more trained nurses. 我们需要更多的受过训练的护士.
Things seen from behind seem a little different. 从背后看到的东西显得稍有不同.
⑵ 用作表语：分词用作表语时,已经完全形容词化了,可以被very, rather等副词修饰,而且可以有比较等级.例如：
The story of his life sounds (very) interesting. 他的生平故事听起来很有趣.
That was the most exciting film of the year. 那是一年中最激动人心的电影.
请比较：
This cup is broken. How about that one? 这只杯子是破的,那只怎么样?（系表结构）
The cup was broken by my brother. 杯子被我弟弟打破了. （被动语态）
⑶ 用作宾语补足语：分词作宾语补足语时,用于表示感觉、致使的动词,如：see, watch, hear, feel, smell, notice, find; have, get, leave, keep等.例如：
I saw him talking with the doctor. 我看见他在跟医生讲话.
He kept the machine running for ten hours. 他使得机器一直转了10个小时.
We have never seen the mountain covered in snow. 我们从未见那座山被雪覆盖过.
请比较：
I saw the old man crossing the street. 我看见那个老人在过街. （表示动作正在进行）
I saw the old man cross the street. 我看见那个老人过街的. （表示动作已发生过）
⑷ 用作状语：分词用作状语,具有多种语义.例如：
Hearing / When hearing a noise, they stopped talking. (= When they heard….) 听到喧闹声,他们便停止了谈话. （时间状语）
She sat there reading a newspaper. (= … and read a newspaper.) 她坐在那里看报纸. （伴随状况状语）
Deeply moved, she couldn’t say a word. (= As she was deeply moved….) 她深受感动,一句话也说不出来. （原因状语）
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动名词
1 动名词的形式
动名词的形式跟现在分词一样,由“动词原形＋-ing”构成,例如：do → doing, study → studying, close → closing, stop → stopping.注意加-ing的不同情况.
2 动名词的用法
动名词或动名词短语具有名词的功能,在句中可用作多种名词性成分.
⑴ 用作主语：跟不定式一样,动名词作主语时常位于句末,而在其原来的位置用it作形式主语.例如：
Saying so much is useless.
It is useless saying so much.
说这么多没有用处.
Swimming in the sea is his favourite sport.
It is his favourite sport swimming in the sea.
在大海里游泳是他最喜爱的运动.
⑵ 用作表语：动名词用作表语表示主语是什么,而不是主语的性质或特征如何.例如：
My greatest pleasure is traveling. 我最大的乐趣就是旅游.
One of his bad habits is biting nails. 他的一个坏习惯是咬手指甲.
⑶ 用作动词宾语：只能接动名词而不能接不定式作宾语的动词有：enjoy, finish, keep, mind, miss, practise, stop, suggest等等.例如：
She enjoys going to the cinema. 她喜爱看电影.
He keeps making the same mistakes. 他老是犯同样的错误.
I suggest leaving now. (= … that we leave now.) 我建议（我们）现在就离开.
⑷ 用作介词宾语：与介词一起用作状语等,也可用在部分形容词后.例如：
After finishing my work, I took a short rest. 干完活后,我休息了一小会儿.
They drove into town without talking to each other. 他们开车进城,一路上彼此默默无言.
All the students are sure of passing the examination. 所有的学生都自信能通过考试.
⑸ 用作定语：动名词作定语时不带附加成分,通常前置,表示该名词所表示的事物的用途.如果用“for＋动名词”,则应后置.例如：
a swimming pool = a pool for swimming 游泳池
a teaching building = a building for teaching 教学楼
另请比较：
the working conditions = the conditions for working 工作条件 （动名词）
the working people = the people who are working 劳动人民 （现在分词）
3 动名词作宾语和不定式作宾语的比较
有些及物动词后面既可以接动名词作宾语,又可以接不定式作宾语,其中不少动词还会引起意思上的变化.
⑴ begin, start等：
在begin, start, hate, like, love, prefer等动词后,用动名词或不定式作宾语,意思上几乎没有什么区别.例如：
The teacher said, “You begin writing now,” and the children began to write. 老师说,“你们现在就开始写吧.”于是孩子们就开始写了.
Will you start reading / to read? 你开始读好吗?
So you prefer living / to live abroad? 所以你宁愿住在国外是吗?
有时,like后接动名词时,表示经常性的爱好；后接不定式时,表示一次性的或独特的爱好.例如：
I like traveling and, especially, to travel with friends. 我喜欢旅行,特别是和朋友们一起旅行.
He doesn’t like reading, but he likes to read newspapers in bed. 他不喜欢读书,但是他喜欢在床上看报.
⑵ forget, remember等：
在forget, remember后,用动名词作宾语表示已做过的事情,用不定式表示要去做的事情.例如：
I remember posting the letter. 我记得把信寄走了.
Remember to post the letter. 别忘了把信寄走.
I will never forget seeing him for the first time. 我永远不会忘记首次见到他的情景.
He forgot which way to go. 他忘了该走哪一条道.
⑶ stop, go on等：
在stop, go on后,用动名词作宾语表示“（停止或继续）做同一件事”,用不定式表示“（停下来或接下去）做另一件事”.例如：
They stopped talking. 他们停止了谈话.
They stopped to talk. 他们（停止原来做的事）开始谈话.
The teacher asked us to go on reading. 老师要我们继续读书.
The teacher asked us to go on to read. 老师要我们接下去读书.
⑷ need, want等：
在need, want后,用动名词作宾语具有被动意义,和用被动态的不定式在意义上一样.例如：
This room needs cleaning / to be cleaned. 这间房间需要打扫.
The old watch wants repairing / to be repaired. 这块旧表需要修理.