作业帮不定式不可以在句子中做什么成分
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不定式不可以在句子中做什么成分
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.结构：动词 + 不定式
2.用途：
动词不定式在句中可以作句子除谓语之外的任何句子成分.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. [编辑本段][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 do（not) to be done
进行式 （not) to be doing无被动
完成式 （not) to have done ( not) to have been done
(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.（不定式作主语是被动语态to be invited是被邀请）
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 take 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.
一般在情绪后加to do to do 也表将来 [编辑本段][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. [编辑本段][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) 以下动词后,只能跟不定式作宾语
afford （付得起）,agree（同意）,aim(力求做到), appear（显得）,arrange（安排）,ask（要求）,attempt （试图）,care（想要）,choose（决定）,claim（声称）,condescend（屈尊）,consent（准许）,decide（决定）,demand（要求）,determine（决心）,endeavor（竭力）,expect（期待）,fail（未履行）,help（帮助）,hesitate（犹豫）,hope（希望）,learn（学会）,manage（设法）,neglect（疏忽）,offer（主动提出）,plan（计划）,prepare（准备）,pretend（假装）,proceed（接着做）,promise（答应）,prove（证明）,refuse（拒绝）,resolve（解决）,seem（觉得好像）,swear（发誓）,tend（往往会）,threaten（预示）,undertake（承诺）,volunteer（自愿做）,vow（发誓）,want（想要）,wish（希望） pretend
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+疑问词+ 不定式
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.
3)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.
I find it difficult to learn English well.
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.
四、作表语
不定式作表语表示具体动作或将来动作；动名词作表语表示抽象的一般行为.
①To be kind to the enemy is to be cruel to the people.
②My chief purpose is to point out the difficulties of the matter.
③What I would suggest is to put off the meeting.
当主语和表语都是不定式时,其含义一是条件,一是结果（例①）.当主语是aim,duty,hope,idea,mista ke,plan,purpose,suggestion等为中心词的名词词组（例②）时,或以what引导的名词性分句（例③）,不定 式说明主语的内容.
④Our work is serving the people.
⑤What he likes is taking a walk after supper.
⑥The story told by Mr.Wang is interesting.
④⑤句动名词作表语,与主语部分可以转换,如Serving thepeople is our work,而⑥句中是现在分词作 表语,说明主语的性质、状态,现在分词具有形容词的各种特征,另外,动名词作表语还应与进行时态区别开 来.
五、作状语
1）目的状语
To… only to (仅仅为了), in order to, so as to, so(such)… as to… (如此……以便……)
He ran so fast as to catch the first bus. 他飞快地跑以便赶上第一班车.
I come here only to say good-bye to you. 我来仅仅是向你告别.
2）作结果状语,表事先没有预料到的,要放在句子后面.
What have I said to make you angry.
He searched the room only to find nothing.
3) 表原因
I'm glad to see you.
典型例题
The chair looks rather hard, but in fact it is very comfortable to ___.
A. sit B. sit on C. be seat D. be sat on
答案：B. 如果不定式为不及物动词,其后应有必要的介词.当动词与介词连用时,常位于"形容词+动词不定式"结构的末尾.
六、作定语
⒈不定式作定语
不定式在句中作定语,置于被修饰的名词或代词之后.如：
①The next train to arrive is from Washington.
②Do you have anything to be taken to your sister?
③Do you have anything to say on the question?
④Would you please give me some paper to write on?
⑤My wish to visit France has come true at last.
不定式短语作定语和被修饰词之间表示以下关系：
(1)表示将来的动作（例①）.
(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（例④）.
(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（例③）；如只有动宾关系,而无逻辑上的主谓关系,则需用被动语态（例②）.
(4)不定式作定语时,一般可转换为定语从句,例①to arrive=that will arrive. [编辑本段][省to 的动词不定式] 1） 情态动词 ( 除ought 外,ought to)：
2） 使役动词 let, have, make：
3） 感官动词 see, watch, look at, notice , observe, hear, listen to, smell, feel, find 等后作宾补,省略to.
8 be afraid doing/to do
be afraid to do 不敢,胆怯去做某事,是主观上的原因不去做,意为"怕"；
be afraid of doing 担心出现doing的状况、结果. doing 是客观上造成的,意为"生怕,恐怕".
She was afraid to step further in grass because she was afraid of being
bitten by a snake.
她生怕被蛇咬着,而不敢在草丛中再走一步.
She was afraid to wake her husband.
她不敢去叫醒她丈夫.
She was afraid of waking her husband.
她生怕吵醒她丈夫.
.9 be interested doing/to do
interested to do 对做某事感兴趣,想了解某事.
interested in doing 对某种想法感兴趣,doing 通常为想法.
I shall be interested to know what happens.
我很想知道发生了什么事. (想了解)
I'm interested in working in Switzerland. Do you have any idea about that?
我对在瑞士工作感兴趣.你想过这事吗? (一种想法)
10 mean to doing/to do
mean to do 打算、想
mean doing 意味着
I mean to go, but my father would not allow me to.
我想去,但是我父亲不肯让我去.
To raise wage means increasing purchasing power.
赠加工资意味着增加购买力.
11 begin(start) doing/to do
begin / start to do sth
begin / start doing sth.
1) 谈及一项长期活动或开始一种习惯时,使用doing.
How old were you when you first started playing the piano?
你几岁时开始弹钢琴?
2) begin, start用进行时时,后面动词用不定式to do
I was beginning to get angry.
我开始生起气来.
3) 在attempt, intend, begin, start 后接know, understand, realize这类动词时,常用不定式to
do.
I begin to understand the truth.
我开始明白真相.
4) 物作主语时
It began to melt.
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.结构：动词 + 不定式
2.用途：
动词不定式在句中可以作句子除谓语之外的任何句子成分.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. [编辑本段][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 do（not) to be done
进行式 （not) to be doing无被动
完成式 （not) to have done ( not) to have been done
(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.（不定式作主语是被动语态to be invited是被邀请）
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 take 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.
一般在情绪后加to do to do 也表将来 [编辑本段][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. [编辑本段][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) 以下动词后,只能跟不定式作宾语
afford （付得起）,agree（同意）,aim(力求做到), appear（显得）,arrange（安排）,ask（要求）,attempt （试图）,care（想要）,choose（决定）,claim（声称）,condescend（屈尊）,consent（准许）,decide（决定）,demand（要求）,determine（决心）,endeavor（竭力）,expect（期待）,fail（未履行）,help（帮助）,hesitate（犹豫）,hope（希望）,learn（学会）,manage（设法）,neglect（疏忽）,offer（主动提出）,plan（计划）,prepare（准备）,pretend（假装）,proceed（接着做）,promise（答应）,prove（证明）,refuse（拒绝）,resolve（解决）,seem（觉得好像）,swear（发誓）,tend（往往会）,threaten（预示）,undertake（承诺）,volunteer（自愿做）,vow（发誓）,want（想要）,wish（希望） pretend
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+疑问词+ 不定式
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.
3)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.
I find it difficult to learn English well.
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.
四、作表语
不定式作表语表示具体动作或将来动作；动名词作表语表示抽象的一般行为.
①To be kind to the enemy is to be cruel to the people.
②My chief purpose is to point out the difficulties of the matter.
③What I would suggest is to put off the meeting.
当主语和表语都是不定式时,其含义一是条件,一是结果（例①）.当主语是aim,duty,hope,idea,mista ke,plan,purpose,suggestion等为中心词的名词词组（例②）时,或以what引导的名词性分句（例③）,不定 式说明主语的内容.
④Our work is serving the people.
⑤What he likes is taking a walk after supper.
⑥The story told by Mr.Wang is interesting.
④⑤句动名词作表语,与主语部分可以转换,如Serving thepeople is our work,而⑥句中是现在分词作 表语,说明主语的性质、状态,现在分词具有形容词的各种特征,另外,动名词作表语还应与进行时态区别开 来.
五、作状语
1）目的状语
To… only to (仅仅为了), in order to, so as to, so(such)… as to… (如此……以便……)
He ran so fast as to catch the first bus. 他飞快地跑以便赶上第一班车.
I come here only to say good-bye to you. 我来仅仅是向你告别.
2）作结果状语,表事先没有预料到的,要放在句子后面.
What have I said to make you angry.
He searched the room only to find nothing.
3) 表原因
I'm glad to see you.
典型例题
The chair looks rather hard, but in fact it is very comfortable to ___.
A. sit B. sit on C. be seat D. be sat on
答案：B. 如果不定式为不及物动词,其后应有必要的介词.当动词与介词连用时,常位于"形容词+动词不定式"结构的末尾.
六、作定语
⒈不定式作定语
不定式在句中作定语,置于被修饰的名词或代词之后.如：
①The next train to arrive is from Washington.
②Do you have anything to be taken to your sister?
③Do you have anything to say on the question?
④Would you please give me some paper to write on?
⑤My wish to visit France has come true at last.
不定式短语作定语和被修饰词之间表示以下关系：
(1)表示将来的动作（例①）.
(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（例④）.
(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（例③）；如只有动宾关系,而无逻辑上的主谓关系,则需用被动语态（例②）.
(4)不定式作定语时,一般可转换为定语从句,例①to arrive=that will arrive. [编辑本段][省to 的动词不定式] 1） 情态动词 ( 除ought 外,ought to)：
2） 使役动词 let, have, make：
3） 感官动词 see, watch, look at, notice , observe, hear, listen to, smell, feel, find 等后作宾补,省略to.
8 be afraid doing/to do
be afraid to do 不敢,胆怯去做某事,是主观上的原因不去做,意为"怕"；
be afraid of doing 担心出现doing的状况、结果. doing 是客观上造成的,意为"生怕,恐怕".
She was afraid to step further in grass because she was afraid of being
bitten by a snake.
她生怕被蛇咬着,而不敢在草丛中再走一步.
She was afraid to wake her husband.
她不敢去叫醒她丈夫.
She was afraid of waking her husband.
她生怕吵醒她丈夫.
.9 be interested doing/to do
interested to do 对做某事感兴趣,想了解某事.
interested in doing 对某种想法感兴趣,doing 通常为想法.
I shall be interested to know what happens.
我很想知道发生了什么事. (想了解)
I'm interested in working in Switzerland. Do you have any idea about that?
我对在瑞士工作感兴趣.你想过这事吗? (一种想法)
10 mean to doing/to do
mean to do 打算、想
mean doing 意味着
I mean to go, but my father would not allow me to.
我想去,但是我父亲不肯让我去.
To raise wage means increasing purchasing power.
赠加工资意味着增加购买力.
11 begin(start) doing/to do
begin / start to do sth
begin / start doing sth.
1) 谈及一项长期活动或开始一种习惯时,使用doing.
How old were you when you first started playing the piano?
你几岁时开始弹钢琴?
2) begin, start用进行时时,后面动词用不定式to do
I was beginning to get angry.
我开始生起气来.
3) 在attempt, intend, begin, start 后接know, understand, realize这类动词时,常用不定式to
do.
I begin to understand the truth.
我开始明白真相.
4) 物作主语时
It began to melt.