实用英语语法 第二十讲（非谓语动词 动词不定式）
实用英语语法
第二十讲
非谓语动词 动词不定式
非谓语动词
中英文里动词除了做谓语之外，也可能做主语，宾语，表语，宾语补足语，定语和状语。不过中文里动词是没有词形变化的，而在英语里，非谓语动词是有词形变化的，我们一定要用动词不定式：to do，现在分词，动名词doing和过去分词done形式。
非谓语动词是英汉主要差异之一，也是下面我们分别学习。
一. 动词不定式
动词不定式由“不定式符号to+动词原形”构成。在某些情况下，to也可以省略。
My work is to teacher English .
我的工作是教英语。
There is a lot of work to do (to be done) today.
今天有很多工作要做。
She seems to enjoy her work.
她似乎很喜欢她的工作。
When to leave for London is up to you.
什么时候去伦敦由你决定。
一般从时间上看，动词不定式动作是没有发生的，但因为有些词后必须跟不定式结构，但又表达不同的时间，语态的，动词不定式就有一些形式的变化：
被动式 to be done
进行式 to be doing
完成式 to have done to have been done
完成进行式 to have been doing
He seems to be thinking of something.
他好像在想什么。
It"s a great honour to be invited to your conference.
很荣幸被邀请参加你们的会议。
I"m sorry to have bothered you so much.
很抱歉打扰了你这么久。
动词不定式在句子中可以做主语，宾语，表语，宾语补足语，定语和状语。
作主语
To travel by train is the safest way.
坐火车旅行是最安全的方式。
To lean out of the window is forbidden.
禁止探出窗外。
我们经常会用it作形式主语，把真正的主语不定式置于句后。如：
(It"s) nice to meet you.
很高兴见到你。
It"s impolite to interrupt a person.
打断别人是不礼貌的。
It takes me half an hour to go to school by bike.
我骑自行车上学要半个小时。
He found it was hard to get used to the new school.
他发现很难适应新学校。
It"s our duty to protect the environment.
保护环境是我们的责任。
It seems impossble for me to rent an ideal flat.
我似乎不可能租一套理想的公寓。
当句子中形容词既修饰动词不定式，也可以修饰这个人时，用介词of而不是for:
It"s very kind of you to help me with my luggage.
你帮我拿行李真是太好了。
It"s silly of you to give up the chance.
你放弃这个机会真傻。
这是最最常用的一个句型哦。
作宾语
谓语动词后再跟动词做宾语，有些只用动词不定式，有些只跟动名词，而有的两种形式都可能。
跟动名词的动词记住了，其他的就是只能跟不定式作宾语的了：
He failed to arrive at the airport on time.
他未能按时到达机场。
I happen to know the man over there.
我碰巧认识那边的那个人。
We all agreed to go there by train.
我们都同意乘火车去那里。
I promised to work hard at school.
我答应在学校努力学习。
We are hoping to visit Paris in the summer.
我们希望在夏天游览巴黎。
I"m sorry to have kept you waiting for so long.
很抱歉让你久等了。
They seemed to be discussing something important.
他们似乎在讨论一些重要的事情。
作补语
形容词，介词短语，现在分词，过去分词都可以做宾语补足语。
在被动句里，原来的宾语成了主语，补足语就成了主语补足语。
My parents allowed us to play in the stream.
我父母允许我们在小溪里玩耍。
We were not allowed to play in the stream.
我们不能在小溪里玩耍。
Some students find it difficult to learn English well.
有些学生发现学好英语很困难。
The head teacher told us to turn off the lights before leaving.
班主任让我们在离开前把灯关掉。
We would like you to come to our party.
我们希望你来参加我们的聚会。
I didn"t expect there to be so many people in the market.
我没想到市场里会有这么多人。
注意：
以下动词的宾语补足语，要省略to，用动词原形
看see/watch/notice/observe/look at；
听hear/listen to
使役 have/make/let
I saw a boy run on the playground.
我看见一个男孩在操场上奔跑。
I had my mother buy a new schoolbag for me.
我让妈妈给我买了一个新书包。
He made the dog learn to play frisby.
我让那条狗学会了玩飞盘。
Have you heard him sing in his room?
你听见他在房间里唱歌了吗？
We often hear his father shout at him.
我们经常听到他父亲对他大喊大叫。
被动句里，主语补足语要还原to
She is often seen to walk to school by herself.
人们经常看到她独自步行上学。
The workers are made to work extra hours everyday.
工人们被迫每天加班。
但是：
Let the girl try it again.
The girl is let try again.
让那个女孩再试一次。
作表语
不定式作表语表示具体动作或将来动作。
Our aim is to win the first prize.
我们的目标是赢得一等奖。
The question is how to put it into practice.
问题是如何将其付诸实践。
My advice is to eat out tonight.
我的建议是今晚出去吃饭。
作状语
目的状语 动词不定式做状语，最常用来表达目的：
In order to save his life, the doctors were operating on his heart.
为了救他，医生们对他的心脏进行了手术。
He did all this to help her.
他这么做是为了帮助她。
I exercise every day so as to keep fit.
我每天锻炼身体以保持健康。
We walked silently so as not to disturb anyone.
We walked so silently as not to disturb anyone.
She smiled at me only to be polite.
作结果状语，表事先没有预料到的，要放在句子后面。
The passengers waited for an hour only to be told the flight had been cancelled.
乘客们等了一个小时才得知航班取消了。
作定语
不定式在句中作定语，置于被修饰的名词或代词之后。如：
The next thing to do is to find a hotel.
接下来要做的就是找到一家旅馆。
There is nothing to be worried about.
没什么好担心的。
I have nothing to worry about.
我没什么好担心的。
Give me some paper to write on.
给我一些纸写。
不定式短语作定语是一个难点，请注意不定式和被修饰词之间的关系：
(1)表示将来的动作。
(2)与被修饰词之间有动宾关系，如是不及物动词，则需加介词。
(3)与被修饰词之间有动宾关系，同时与句中其它词之间又有逻辑上的主谓关系时，尽管有被动含义，却仍 用主动语态；如只有动宾关系，而无逻辑上的主谓关系，则需用被动语态。
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