百度作业网动词不定式有什么作用?
来源：学生作业帮 编辑：百度作业网作业帮 分类：英语作业 时间：2024/05/28 11:03:38
动词不定式有什么作用?
1. 不定式定义:由to＋动词原形构成.
不定式是一种非限定性动词.而非限定动词是指那些在句中不能单独充当谓语的动词,可分为不定式,动名词,现在分词和过去分词.
2.用途：
在句中不能作谓语.它具有动词的性质,本身可以带宾语和状语.
【动词不定式】
1.定义：动词 + 不定式
2.用途：
动词不定式在句中可以作句子任何成分.动词不定式的被动形式除了一般形式外还有其完成式和进行式.
[动词不定式的时态、语态]
动词不定式可以作以上各种成分,但它毕竟是动词,所以有动词的属性
动词不定式及其短语还可以有自己的宾语、状语,虽然动词不定式在语法上没有表面上的直接主语,但它表达的意义是动作,这一动作一定由使动者发出.这一使动者我们称之为 逻辑主语,其形式如下：
主动形式 被动形式
一般式 （not) to make （not) to be made
完成式 （not) to have made ( not) to have been made
进行式 （not) to be making （not） to have been making
(1)语态
如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者,不定式一般要用被动语态形式.如：
It's a great honour to be invited to Mary's birthday party.（不定式作主语）
It was impossible for lost time to be made up.（不定式作主语）
I wish to be sent to work in the country.（不定式作宾语）
Can you tell me which is the car to be repaired?（不定式作定语）
He went to the hospital to be examined.（不定式作状语）
在There be结构中,修饰主语的不定式可用被动,也可用主动.如：There are still many things to t ake care of (to be taken care of).但有时两种形式表达的意思不同,如：These is nothing to do now.( We have nothing to do now.) There is nothing to be done now.(We can do nothing now.)
(2)时态
1) 现在时：一般现在时表示的动词,有时与谓语动词表示的动作同时发生,有时发生在谓语动词的动作之后.
He seems to know this.
I hope to see you again. = I hope that I'll see you again. 我希望再见到你.
2) 完成时：表示的动作发生在谓语动词表示的动作之前.
I'm sorry to have given you so much trouble.
He seems to have caught a cold.
3) 进行时： 表示动作正在进行,与谓语动词表示的动作同时发生.
He seems to be eating something.
4) 完成进行时：
She is known to have been wreaking on the problem for many years.
[疑问词＋不定式结构]
疑问词who,what,which,when,where,whether,how后可接不定式构成不定式短语,在句中作主语、宾语、表 语等.如：
①When to leave for London has not been decided yet. （不定式在句子中做主语）
②Mr. Smith didn't know whether to leave or stay there. （不定式在句子中做宾语）
③I asked Professor Xu how to learn English well. （不定式在句子中做间接宾语）
④The question was where to get the medicine needed. （不定式在句子中表语）
以上例句中疑问词＋不定式部分,均可转换为相应的从句形式.如：①When we shall leave…③…how I
could learn…
经常在这种结构中使用的动词有：consider,decide,discover,explain,find out,forget,hear,know,lea rn,observe,understand,wonder等.
[动词不定式的语法功能]
一、作主语
动词不定式作主语时,句子的谓语动词常用单数,其位置有以下两种：
(1)把不定式置于句首.如：
To get there by bike will take us half an hour.
(2)用it作形式主语,把真正的主语不定式置于句后,常用于下列句式中.如：
①It＋be＋名词＋to do
It's our duty to take good care of the old.
②It takes sb+some time+to do
How long did it take you to finish the work?
③It＋be＋形容词＋for sb＋to do
It is difficult for us to finish writing the compositionin a quarter of an hour.
④It＋be＋形容词＋of sb＋to do
It is stupid of you to write down everything the teachersays.
⑤It seems(appears)＋形容词＋to do
It seemed impossible to save money.
在句型③中,常用表示客观情况的形容词,如：difficult,easy,hard,important,impossible,necessary 等；在句型④中,常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词.在不定式前的sb,可看作其逻辑主语.这一句式有时相当于Sb is＋形容词＋to do句式 ,如：It'skind of you to help me with my English.=You are kind to helpme with my English.
(3)举例
1） It's easy (for me) to do that.我做这事太容易了
easy, difficult, hard, important, possible, impossible, comfortable, necessary, better;
the first, the next, the last, the best, too much, too little, not enough
It's so nice to hear your voice.
听到你的声音真高兴.
It's necessary for you to lock the car when you do not use it.
当你不用车的时候,锁车是有必要的.
2) It's very kind of him to help us. 他帮助我们,他真好.
Kind, nice, stupid, rude, clever, foolish, thoughtful, thoughtless, brave, considerate(考虑周到的), silly, selfish(自私的)
例句:
It was silly of us to believe him. 我们真愚蠢,竟然相信了他.
It seemed selfish of him not to give them anything. 他不给他们任何东西,这显得太自私了.
注意：1) 其他系动词如,look,appear等也可用于此句型
2) 不定式作为句子成分时,动词用单数形式.
3) 当不定式作主语的句子中又有一个不定式作表语时,不能用It is… to…的句型
(对)To see is to believe. 百闻不如一见.
(错)It is to believe to see.
二、作宾语
1) 动词+ 不定式
afford. aim. appear. agree. arrange . ask . be . decide. bother . care . choose . come. dare. demand. desire. determine . expect. elect . endeavor .hope. fail . happen . help . hesitate .learn . long . mean. manage . offer . ought. plan . prepare. pretend . promise. refuse. seem. tend. wait . wish. undertake.
举例：
The driver failed to see the other car in time.
司机没能及时看见另一辆车.
I happen to know the answer to your question.
我碰巧知道你那道问题的答案.
2）动词+不定式 ；动词+宾语+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜欢每件东西都保持整洁.
I like you to keep everything tidy. 我喜欢你使每件东西都保持整洁.
I want to speak to Tom. 我想和汤姆谈话.
I want you to speak to Tom. 我想让你和汤姆谈话.
3） 动词+疑问词+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please show us how to do that. 请演示给我们如何去做.
There are so many kinds of tape-recorders on sale that I can't make up my mind which to buy.有这么多的录音机,我都拿不定主意买哪一种.
注意:疑问词带不定式在句中作成分时,谓语动词用单数.
The question is how to put it into practice.
问题是怎样把它付诸实施.
4)以下动词后,只能跟不定式作宾语.
如：agree,ask,aim,arrange,choose,decide,demand,expect,fail ,help,hope,learn,long,manage,offer,plan,prepare,
pretend,promise,refuse,wish 等,这些词大部分可接that引导的从句.如：
I decided to ask for my money back.
I decided that I would ask for my money back.
When our visit to the farm was over,we expected to startback on foot.
When our visit to the farm was over, we expected that wewould start back on foot.
5)当复合宾语中的宾语是不定式时,先用形式宾语it代替不定式,把不定式置于补语之后,即：主语＋动 词＋it＋补语＋to do句式.如：
We think it quite important for us to learn a foreignlanguage well.
He feels it his duty to help the poor.
三、作补语
1) 动词+宾语+不定式(to do)
advise allow appoint believe cause challenge command compel consider declare drive enable encourage find forbid force guess hire imagine impel induce inform instruct invite judge know like order permit persuade remind report request require select send state suppose tell think train trust understand urge warn
例句：
a. Father will not allow us to play on the street.
父亲不让我们在街上玩耍.
b. We believe him to be guilty.
我们相信他是有罪的.
Find 的特殊用法：
Find 后可用分词做宾补,或先加形式宾语,再加形容词,最后加带to 的动词不定式.find后也可带一个从句.此类动词还有get,have.
I found him lying on the ground.
I found it important to learn.
I found that to learn English is important.
典型例题:
The next morning she found the man ___ in bed,dead.
A. lying B. lie C. lay D. laying
答案：A.find的宾语后面,用分词或分词短语,起宾语补足语作用.现在分词表达主动,也表达正在进行,过去分词表达被动.
2) to + be 的不定式结构,作补语的动词.
Acknowledge, believe, consider, think, declare(声称), discover, fancy(设想), feel find, guess, judge, imagine, know, prove, see(理解), show, suppose, take(以为), understand
We consider Tom to be one of the best students in our class.
我们认为汤姆是班上最好的学生之一.
典型例题
Charles Babbage is generally considered ___ the first computer.
A. to invent B. inventing C. to have invented D. having invented
答案：A. 由consider to dosth. 排除B、D.. 此句只说明发明这一个事实,不定式后用原形即可.而C为现在完成时,发明为点动词一般不用完成时,且此处也不强调对现在的影响,因此不选C.
3) to be +形容词
Seem, appear, be said, be supposed, be believed, be thought, be known, be reported, hope, wish, desire, want, plan, expect, mean…
The book is believed to be uninteresting.
人们认为这本书没什么意思.
4) there be+不定式
believe, expect, intend, like, love, mean, prefer, want, wish, undrstand
We didn't expect there to be so many people there.我们没料到会有那么多人在哪里.
有些动词需用as 短语做补语,如regard, think believe, take, consider.
We regard Tom as our best teacher. 我们认为汤姆是我们最好的老师.
Mary took him as her father . 玛丽把他当作自己的父亲.
不定式是一种非限定性动词.而非限定动词是指那些在句中不能单独充当谓语的动词,可分为不定式,动名词,现在分词和过去分词.
2.用途：
在句中不能作谓语.它具有动词的性质,本身可以带宾语和状语.
【动词不定式】
1.定义：动词 + 不定式
2.用途：
动词不定式在句中可以作句子任何成分.动词不定式的被动形式除了一般形式外还有其完成式和进行式.
[动词不定式的时态、语态]
动词不定式可以作以上各种成分,但它毕竟是动词,所以有动词的属性
动词不定式及其短语还可以有自己的宾语、状语,虽然动词不定式在语法上没有表面上的直接主语,但它表达的意义是动作,这一动作一定由使动者发出.这一使动者我们称之为 逻辑主语,其形式如下：
主动形式 被动形式
一般式 （not) to make （not) to be made
完成式 （not) to have made ( not) to have been made
进行式 （not) to be making （not） to have been making
(1)语态
如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者,不定式一般要用被动语态形式.如：
It's a great honour to be invited to Mary's birthday party.（不定式作主语）
It was impossible for lost time to be made up.（不定式作主语）
I wish to be sent to work in the country.（不定式作宾语）
Can you tell me which is the car to be repaired?（不定式作定语）
He went to the hospital to be examined.（不定式作状语）
在There be结构中,修饰主语的不定式可用被动,也可用主动.如：There are still many things to t ake care of (to be taken care of).但有时两种形式表达的意思不同,如：These is nothing to do now.( We have nothing to do now.) There is nothing to be done now.(We can do nothing now.)
(2)时态
1) 现在时：一般现在时表示的动词,有时与谓语动词表示的动作同时发生,有时发生在谓语动词的动作之后.
He seems to know this.
I hope to see you again. = I hope that I'll see you again. 我希望再见到你.
2) 完成时：表示的动作发生在谓语动词表示的动作之前.
I'm sorry to have given you so much trouble.
He seems to have caught a cold.
3) 进行时： 表示动作正在进行,与谓语动词表示的动作同时发生.
He seems to be eating something.
4) 完成进行时：
She is known to have been wreaking on the problem for many years.
[疑问词＋不定式结构]
疑问词who,what,which,when,where,whether,how后可接不定式构成不定式短语,在句中作主语、宾语、表 语等.如：
①When to leave for London has not been decided yet. （不定式在句子中做主语）
②Mr. Smith didn't know whether to leave or stay there. （不定式在句子中做宾语）
③I asked Professor Xu how to learn English well. （不定式在句子中做间接宾语）
④The question was where to get the medicine needed. （不定式在句子中表语）
以上例句中疑问词＋不定式部分,均可转换为相应的从句形式.如：①When we shall leave…③…how I
could learn…
经常在这种结构中使用的动词有：consider,decide,discover,explain,find out,forget,hear,know,lea rn,observe,understand,wonder等.
[动词不定式的语法功能]
一、作主语
动词不定式作主语时,句子的谓语动词常用单数,其位置有以下两种：
(1)把不定式置于句首.如：
To get there by bike will take us half an hour.
(2)用it作形式主语,把真正的主语不定式置于句后,常用于下列句式中.如：
①It＋be＋名词＋to do
It's our duty to take good care of the old.
②It takes sb+some time+to do
How long did it take you to finish the work?
③It＋be＋形容词＋for sb＋to do
It is difficult for us to finish writing the compositionin a quarter of an hour.
④It＋be＋形容词＋of sb＋to do
It is stupid of you to write down everything the teachersays.
⑤It seems(appears)＋形容词＋to do
It seemed impossible to save money.
在句型③中,常用表示客观情况的形容词,如：difficult,easy,hard,important,impossible,necessary 等；在句型④中,常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词.在不定式前的sb,可看作其逻辑主语.这一句式有时相当于Sb is＋形容词＋to do句式 ,如：It'skind of you to help me with my English.=You are kind to helpme with my English.
(3)举例
1） It's easy (for me) to do that.我做这事太容易了
easy, difficult, hard, important, possible, impossible, comfortable, necessary, better;
the first, the next, the last, the best, too much, too little, not enough
It's so nice to hear your voice.
听到你的声音真高兴.
It's necessary for you to lock the car when you do not use it.
当你不用车的时候,锁车是有必要的.
2) It's very kind of him to help us. 他帮助我们,他真好.
Kind, nice, stupid, rude, clever, foolish, thoughtful, thoughtless, brave, considerate(考虑周到的), silly, selfish(自私的)
例句:
It was silly of us to believe him. 我们真愚蠢,竟然相信了他.
It seemed selfish of him not to give them anything. 他不给他们任何东西,这显得太自私了.
注意：1) 其他系动词如,look,appear等也可用于此句型
2) 不定式作为句子成分时,动词用单数形式.
3) 当不定式作主语的句子中又有一个不定式作表语时,不能用It is… to…的句型
(对)To see is to believe. 百闻不如一见.
(错)It is to believe to see.
二、作宾语
1) 动词+ 不定式
afford. aim. appear. agree. arrange . ask . be . decide. bother . care . choose . come. dare. demand. desire. determine . expect. elect . endeavor .hope. fail . happen . help . hesitate .learn . long . mean. manage . offer . ought. plan . prepare. pretend . promise. refuse. seem. tend. wait . wish. undertake.
举例：
The driver failed to see the other car in time.
司机没能及时看见另一辆车.
I happen to know the answer to your question.
我碰巧知道你那道问题的答案.
2）动词+不定式 ；动词+宾语+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜欢每件东西都保持整洁.
I like you to keep everything tidy. 我喜欢你使每件东西都保持整洁.
I want to speak to Tom. 我想和汤姆谈话.
I want you to speak to Tom. 我想让你和汤姆谈话.
3） 动词+疑问词+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please show us how to do that. 请演示给我们如何去做.
There are so many kinds of tape-recorders on sale that I can't make up my mind which to buy.有这么多的录音机,我都拿不定主意买哪一种.
注意:疑问词带不定式在句中作成分时,谓语动词用单数.
The question is how to put it into practice.
问题是怎样把它付诸实施.
4)以下动词后,只能跟不定式作宾语.
如：agree,ask,aim,arrange,choose,decide,demand,expect,fail ,help,hope,learn,long,manage,offer,plan,prepare,
pretend,promise,refuse,wish 等,这些词大部分可接that引导的从句.如：
I decided to ask for my money back.
I decided that I would ask for my money back.
When our visit to the farm was over,we expected to startback on foot.
When our visit to the farm was over, we expected that wewould start back on foot.
5)当复合宾语中的宾语是不定式时,先用形式宾语it代替不定式,把不定式置于补语之后,即：主语＋动 词＋it＋补语＋to do句式.如：
We think it quite important for us to learn a foreignlanguage well.
He feels it his duty to help the poor.
三、作补语
1) 动词+宾语+不定式(to do)
advise allow appoint believe cause challenge command compel consider declare drive enable encourage find forbid force guess hire imagine impel induce inform instruct invite judge know like order permit persuade remind report request require select send state suppose tell think train trust understand urge warn
例句：
a. Father will not allow us to play on the street.
父亲不让我们在街上玩耍.
b. We believe him to be guilty.
我们相信他是有罪的.
Find 的特殊用法：
Find 后可用分词做宾补,或先加形式宾语,再加形容词,最后加带to 的动词不定式.find后也可带一个从句.此类动词还有get,have.
I found him lying on the ground.
I found it important to learn.
I found that to learn English is important.
典型例题:
The next morning she found the man ___ in bed,dead.
A. lying B. lie C. lay D. laying
答案：A.find的宾语后面,用分词或分词短语,起宾语补足语作用.现在分词表达主动,也表达正在进行,过去分词表达被动.
2) to + be 的不定式结构,作补语的动词.
Acknowledge, believe, consider, think, declare(声称), discover, fancy(设想), feel find, guess, judge, imagine, know, prove, see(理解), show, suppose, take(以为), understand
We consider Tom to be one of the best students in our class.
我们认为汤姆是班上最好的学生之一.
典型例题
Charles Babbage is generally considered ___ the first computer.
A. to invent B. inventing C. to have invented D. having invented
答案：A. 由consider to dosth. 排除B、D.. 此句只说明发明这一个事实,不定式后用原形即可.而C为现在完成时,发明为点动词一般不用完成时,且此处也不强调对现在的影响,因此不选C.
3) to be +形容词
Seem, appear, be said, be supposed, be believed, be thought, be known, be reported, hope, wish, desire, want, plan, expect, mean…
The book is believed to be uninteresting.
人们认为这本书没什么意思.
4) there be+不定式
believe, expect, intend, like, love, mean, prefer, want, wish, undrstand
We didn't expect there to be so many people there.我们没料到会有那么多人在哪里.
有些动词需用as 短语做补语,如regard, think believe, take, consider.
We regard Tom as our best teacher. 我们认为汤姆是我们最好的老师.
Mary took him as her father . 玛丽把他当作自己的父亲.