动词不定式用法
不定式是动词的一种非限定式，它是不受主语的单复数、人称、等的限定及影响的一种动词形式，但有时态和语态的变化。
一、动词不定式的基本结构
动词不定式的基本形式为：to+动词原形，有时可不带to。
不定式的否定形式是：not to+动词原形。
在句中除不能作谓语外，其他成分都可作。
如：主语、表语、宾语、宾语补足语、定语和状语等。
注意：不定式之前的to（又称为小品词）与介词to的功能不同。
介词to之后要接名词或代词的宾格，或相当于名词的短语作它的宾语；而不定式符号to的后面需要跟动词原形。
speak to him (to 是介词) 对他讲话
to speak English (to 是不定式的小品词) 讲英语
二、动词不定式的用法
不定式在句中有各种作用，一般可归类为三种基本用法：作名词，作形容词，作副词。
(一) 不定式作名词的用法
不定式起名词作用，在句子中担当主语、表语、宾语和宾语补足语。
⒈作主语
名词用法的不定式和名词一样，可担任句子的主语。
To grow more trees here is very important.
(=It is very important to grow more trees here.) 在这里多种些树是非常重要的。
To hear your voice is so nice.
(=It is so nice to hear your voice.) 听到你的声音真高兴。
To speak English well is not easy for me.
(=It is not easy for me to speak English.) 把英语说好对我来说并不容易。
To walk to school takes me twenty minutes.
(=It takes me twenty minutes to walk to school.) 步行到学校我要花20
分钟。
注意：在It is… to…”的句型中，it是形式主语，真正的主语是不定式；使用这种结构，可以避免句子的头重脚轻。
通常不定式被视为第三人称单数，所以动词用is或was。
It is bad for your eyes to read in the sun. 在阳光下看书对你的眼睛有害。
另外，不定式作主语的句子，同时有另外一个不定式作表语时，不能转换成“It is… to…”的句型。
To see is to believe. (百闻不如一见。
)
不能转换为：It is to believe to see.
2.作表语
不定式像名词一样，可以放在be动词后面，形成表语。
My work is to clean the room every day. 我的工作是每天打扫这间屋子。
Her dream is to be a lawyer. 她的梦想就是成为一名律师。
What they want is to do it at once. 他们所想的就是立刻着手做这件事。
附加：
（1）动词不定式往往放在系动词be（，become, sound, taste 等系动词后面一般不接不定式）的后面作表语，表示将来的情况，说明主语的内容。
例如：
My wish is to become a teacher．我的愿望是当一名教师。
Your job today is to clean the playground.
你今天的工作是打扫操场。
（2）如果系动词后的动词说明主语的性质，特征，相当于形容词。
这时就要用现在分词作表语，而不用不定式。
例如：
He said that the story was interesting．他说这则故事很有趣
Nurse’s responsibility is taking care of patients.
3.作宾语
不定式作宾语用在及物动词之后。
常用的及物动词有：want, wish, hope, like, begin, start, help, agree, refuse, promise, learn, forget, know, need, try等。
They began to read and write. 他们开始读和写。
She wanted to get home earlier that day. 她那天想要早一些到家。
They refused to do so. 他们拒绝那样做。
I hope to visit Paris some day. 我希望有一天能参观巴黎。
注意：(1) 在某些复合宾语中，常用“it”代替不定式，而把不定式放到后面去。
He found it very difficult to get to sleep. 他发现很难入睡。
She thinks it important to study English well. 她认为把英语学好很重要。
(2) 在tell, show, teach, find out, decide, learn, forget等动词之后，常用一个带连接代词或副词的不定式作宾语。
He doesn’t know which one to choose. 他不知道应该选哪一个。
My mother used to teach me how to read and write. 过去我母亲常教我如何读书写字。
No one could tell me where to get this kind of bike. 没人告诉我在哪里能找到这种自行车。
4.做宾语补足语
She asked me to speak more loudly.
宾语宾补
Jim told him not to cry. 吉姆告诉他不要哭。
She advised him to do so. 她劝他这么做。
We all know him to be a clever boy. 我们都知道他是一个聪明的孩子。
He reminded me to lock the door when I left. 他提醒我离开时锁上门。
注意：(1) 有一些表示感官的动词，如see, hear, watch, feel, notice和某些使役动词，如let, make, have等，其后跟不定式作宾语补足语时,不定式通常不带to.
He saw Li Ping come into the classroom. 他看见李平走近了教室。
Don’t forget to let her leave earlier. 别忘了让她早点走。
It made me feel thirsty. 这东西让我感到口渴。
但当这些动词用于被动语态时，作主语补足语的不定式要带to. 例如：
He was seen to come into the classroom. 他被看见走进了教室。
I was made to do a lot of homework yesterday. 我昨天被要求做很多家庭作业。
(2) 感官动词后面还可用现在分词作宾语。
区别为：不定式表示动作发生了，侧重全过程；现在分词则表示动作正在进行。
如：
I saw him come in. 我看见他进来了。
I saw him coming in. 我看见他正往里走。
(3) 动词help之后，带to或不带to都可以。
Will you please help me (to) take this suitcase? 请你帮我提一下这个衣箱好吗？
She often helps her mother (to) clean their house. 她经常帮助她妈妈打扫房子。
（二）不定式作形容词的用法——作定语
1. 不定式有时起形容词作用修饰名词或代词，在句中担任定语。
不定式作定语时，它的位置在它所修饰的名词或代词之后。
I have a lot of work to do. 我有许多事情要做。
Have you got anything to say? 你还有什么要说的吗？（something, anything, nothing, everything等复合不定代词常用不定式做后置定语。
）
She is the last to come. 她是最后一个到的。
（当名词前有the first ,the last, the only 等以及最高级时：eg: She is always the first to come and the last to leave.)eg:
He spoke loudly (only to / in order to/so as to) be heard.
比较：He rushed to the station only to find the train gone .(结果状语)
注意：(1) 如果修饰不定代词的还有形容词时，它们的位置应该是：不定代词+形容词+不定式。
I have something important to do. 我有些重要的事要做。
Give me something hot to drink. 给我一些热的东西喝。
(2) 如果不定式是不及物动词，或者不定式修饰的名词或代词是不定式动词的地点、工具等，不定式之后要加一个介词。
This is the best room for you to live in. 这是最适合你住的房间。
There is nothing to worry about. 没什么事情可担心的。
I want to borrow a piece of paper to write on. 我想借张纸写字。
(3) 不定式作定语时，一般可转换为定语从句。
The next train to arrive is from Shanghai. （to arrive=that will arrive）
下一列到站的火车来自上海。
附：不定式主动被动讨论
A)不定式修饰的名词或代词和不定式构成逻辑上的主谓关系时，不定式往往用主动形式.
Have you got a key to unlock the door?
(A key unlocks the door．)
B)不定式和它前面被修饰的名词或代词构成逻辑上的动宾关系，又和该句主语构成逻辑上的主谓关系时，不定式常用主动形式．
I have got a letter to write．( I write letter．)
He needs a room to live in．( He lives in a room．)
I know what to do．( I do what．) 但这句如改为下列形式，不定式就得用被动形式：
I know what is to be done.
这是因为what is to be done是宾语从句，从句中的主语what是动词do的动作对象
C)不定式作表语形容词的状语，和句中主语构成逻辑上的动宾关系时，不定式多用主动形式，这是因为人们往往认为形容词后省去了for one或for people．例如：
He is hard to talk to．( to talk to him．)
The book is difficult to understand. ( to understand the book.) 但如果强调句中的受事者时，亦可用不定式被动式，例如：
The handwriting is very difficult to be read.
The box is too heavy to be lifted．
D)在“there十be”的结构中，当说话人考虑的是必须有人去完成某件事时，不定式用主动形式，如果说话人强调的是事情本身必须完成，则用被动形式．
There is a lot of work to do. ( Somebody has to do the work．)
There is a lot of work to be done．( The work has to be done.)
请注意下面两个句子的含义是不同的：
There is nothing to do. 意为无事可做，感到十分乏味．
There is nothing to be done．意为某东西坏了，无法使之恢复正常．
（三）不定式作副词的用法
不定式可起副词的作用，在句中表目的、结果、原因等。
1. 表目的
He came to teach the little girl English. 他来给这个小女孩上英语课。
I went to visit my uncle last Sunday. 上星期天我去拜访了我的叔叔。
In order to study English well, she often does more speaking and writing.为了把英语学好，她经常多说多写。
2. 表结果
What has he said to make you so sad? 他说了什么话让你这样伤心？
They lifted a rock only to drop in on their own feet. 他们搬起石头砸了自己的脚。
3. 表原因
I am sorry to hear that. 听到这件事，我感到很难过。
The question is quite difficult to answer. 这个问题很难回答。
三、动词不定式的几个重要结构
1. 不定式的否定结构：not +to do
He told me not to be late. 他告诉我别迟到。
She asked the old man not to be angry. 她请这位老人别生气。
注意：不定式否定句不同于否定句形式。
不定式否定句没有助动词，否定句有助动词。
I didn’t ask him to come here. 我没请他来。
I asked him not to come here. 我请他不要来。
2. 不定式的复合结构：for+名词（代词）+不定式
It is very difficult for me to do this job. 对我来说做这件工作很困难。
It is very important for you to practise your oral English in the daily life.
在日常生活中练习你的英语口语是非常重要的。
3. 不定式的“of+名（代）+不定式”结构
It is very nice of you to help me. 你来帮我真是太好了。
It’s kind of you to think so much of us. 难为你这样替我们想。
It was careless of him to lose so many things. 他丢了这么多东西，真是太粗心了。
4. 不定式的“疑问词+不定式”结构
此结构在句中的语法作用有以下几点：
(1) 作主语
How to use the computer is a problem. 如何使用计算机是个问题。
(2) 作表语
The question is how to go to the park. 问题是如何去公园。
(3) 作宾语
I didn’t decide where to go. 我还没有决定去哪儿。
注意：带特殊疑问句的不定式可跟带特殊疑问词的宾语从句进行句型转换。
He didn’t know what to do. =He didn’t know what he should do.
他不知道要做什么。
(4) 作宾语补足语
She often teaches me how to read and write. 她常教我如何读书写字。
（5）作同位语
The problem of which to select as his successor was quickly disposed of.
5. 不定式的“too+形容词或副词+to do sth.”和“too+形容词或副词+for sb/ sth +to do sth.”结构。
She is too young to go to school. 她太小不能上学。
This pair of trousers is too dirty for him to wear. 这条裤子太脏了，他不会穿他的。
(1) too…to结构和too…for…to结构连接句子的区别：
too…to结构连接两个单句中主语相同的句子。
He is too tired. He can’t go any further.
→He is too tired to go any further. 他太累了，再也走不动了。
too…for…to结构连接两个单句中主语不相同的句子。
The box is very heavy. She couldn’t carry i t.
→The box is too heavy for her to carry. 这个箱子太重了，她搬不动。
(2) 这两种句型还可用so…that…(如此……以至于)结构来连接,构成状语从句.
He is so tired that he can’t go any further.
The box is so heavy that he couldn’t carry it.
6. 不定式的“(not)+形容词或副词+enough to”结构和“(not)+形容词或副词+enough for sb/ sth to do.”
这种结构中不定式也用来作状语表结果.意思是“……能够做某事”或“……不能做某事”。
He is old enough to join the army. 他到参军的年龄了。
The little boy doesn’t study English well enough to understand you.这个小男孩英语学得不好，他不懂你的意思。
这种结构可跟“too…to…”结构进行句型互换。
This question was too difficult for everybody in our class to answer.这个问题太难了，我们班的所有人都回答不上来。
→This question was not easy enough for everybody in our class to answer.
这个问题不太容易，我们班的所有人都回答不上来。
四、省略动词不定式符号to的几种情况
1. had bette r…/ Why not…? / Will you please…?/ Shall we…? / Let…等句型后接动词原形。
2. 感官动词see/ hear/ watch/ notice等和使役动词make/ have/ let等后接动词原形做宾补。
3. help后接动词不定式作宾补时的to可省也可不省。
4. would rather后接动词原形。
如：
I would rather stay at home than go for a walk. 我宁愿呆在家里而不愿去散步。
注意：为了避免重复，动词不定式中与上文相同部分可以省略掉，但to须保持下来。
(1) —Will you join me in a walk? 你愿意和我一块儿去散步吗？
—I’ll be glad to. 我愿意。
(2) –Did you find the reference books about it? 你找到有关的参考书了吗？
--No, I tried to, but failed. 没有。
我尽力了，但没找到。
不定式的时态、语态
不定式都表发生在过去或现在的将来、目的或结果，有各种时态和语态
一般式 to do /to be done
完成式 to have done /to have been done
进行式 to be doing
完成进行式 to have been doing
（根据语境来判断该用何种时态和语态）
（一）一般式表示动作通常与句子谓语所表示的动作或状态几乎同时发生，或是在它之后发生。
I am glad to see you. 不定式动作与句子的谓语动词同时进行。
一般式被动 It’s an honour for me to be invited.（与句子谓语同时发生）
（这里为什么不用to invite,因为to invite不是修饰me的，不是定语，而是真正主语）
（二）不定式的正在进行时，表前一个动作发生时，不定式所表动作正在发生
Some dogs were found to be looking for food around. 一些狗被发现正在四处寻找食物。
（三）不定式的完成式
1）发生在谓语动词的动作或状态前，常接不定式完成式的动词有
appear to have done
happen to(碰巧 have done
be said to have done,
be reported to have done
be believed to have done
be known to have done
be thought to have done
be sorry to have done
be likely(可能） to have done等.
还可+to have been done/to have been doing
(表一直持续到..,，可能还要继续下去）
如They seemed to have known each other for a long time.
She is said to have learned four foreign languages.
（2）特殊的几个动词+to have done表示过去没有实现的期待或计划
hope to have done（表遗憾，实际没做成”希望做过什么事，而实际没有）） promise to have done（承诺去做什么，而实际没有）
want to have done
expect to have done
plan to have done
should/would like to have done （表未能实现的愿望）
如，
He wanted to have met you at the airport, but he didn’t get there in time. 没接成。
We planned to have done good deeds for the poor people last month. 没做成。
I should/would like to have given her the gift. 没送成。
He would like to have played the violin at the concert. 没演奏成。
（复习，以上是可以接to do的，意思与+to have done不一样）
总之：
（1）不定式一般表将来的目的或结果。
特殊句式中也表同时进行，但必许用to do.
如:happen to do,seem to do
(2)不定式的时态要与不定式前的动词对比，是在之前？后？还是同时或正在进行。
（3）不定式to的省略形式要记住
(4)那些是主动表被动的要记住
（5）实在不行就多读，把他读出语感。
