百科內(nèi)容來自于:
不定式是一種非限定性動(dòng)詞。而非限定動(dòng)詞是指那些在句中不能單獨(dú)充當(dāng)
謂語的動(dòng)詞，可分為不定式，動(dòng)名詞，現(xiàn)在分詞和過去分詞。它具有動(dòng)詞的性質(zhì)，本身可以帶
賓語和
狀語。動(dòng)詞不定式在句中可以作句子任何成分。動(dòng)詞不定式的被動(dòng)形式除了一般形式外還有其完成式和進(jìn)行式。
簡(jiǎn)介
1.不定式定義:
不定式是一種非限定性動(dòng)詞。而
非限定動(dòng)詞是指那些在句中不能單獨(dú)充當(dāng)謂語的動(dòng)詞，可分為不定式，動(dòng)名詞，現(xiàn)在分詞和過去分詞。
2.用途：
在句中不能作謂語。它具有動(dòng)詞的性質(zhì)，本身可以帶賓語和狀語。
3.形式：
動(dòng)詞 + 不定式:由to＋動(dòng)詞原形構(gòu)成。
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
動(dòng)詞不定式在句中可以作句子任何成分。動(dòng)詞不定式的被動(dòng)形式除了一般形式外還有其完成式和進(jìn)行式。
時(shí)態(tài)語態(tài)
動(dòng)詞不定式及其短語還可以有自己的賓語、狀語，雖然動(dòng)詞不定式在語法上沒有表面上的直接主語，但它表達(dá)的意義是動(dòng)作，這一動(dòng)作一定由使動(dòng)者發(fā)出。這一使動(dòng)者我們稱之為 邏輯主語，其形式如下：
主動(dòng)形式 被動(dòng)形式
一般式 （not） to make （not） to be made
完成式 （not） to have made （not） to have been made
進(jìn)行式 （not） to be making
完成進(jìn)行式 （not） to have been making
(1)語態(tài)
如果動(dòng)詞不定式的邏輯主語是這個(gè)不定式所表示的動(dòng)作的承受者，不定式一般要用被動(dòng)語態(tài)形式。如：
It's a great honour to be invited to Mary's birthday party.（不定式作主語）
It was impossible for lost time to be made up.（不定式作主語）
I wish to be sent to work in the country.（不定式作賓語）
Can you tell me which is the car to be repaired?（不定式作定語）
He went to the hospital to be examined.（不定式作狀語）
在There be結(jié)構(gòu)中，修飾主語的不定式可用被動(dòng)，也可用主動(dòng)。如：There are still many things to t ake care of (to be taken care of).但有時(shí)兩種形式表達(dá)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)時(shí)態(tài)
1) 現(xiàn)在時(shí)：一般現(xiàn)在時(shí)表示的動(dòng)詞，有時(shí)與謂語動(dòng)詞表示的動(dòng)作同時(shí)發(fā)生，有時(shí)發(fā)生在謂語動(dòng)詞的動(dòng)作之后。
He seems to know this.
I hope to see you again. = I hope that I'll see you again. 我希望再見到你。
2) 完成時(shí)：表示的動(dòng)作發(fā)生在謂語動(dòng)詞表示的動(dòng)作之前。
I'm sorry to have given you so much trouble.
He seems to have caught a cold.
3) 進(jìn)行時(shí)： 表示動(dòng)作正在進(jìn)行，與謂語動(dòng)詞表示的動(dòng)作同時(shí)發(fā)生。
He seems to be eating something.
4) 完成進(jìn)行時(shí)：
She is known to have been wreaking on the problem for many years.
結(jié)構(gòu)
疑問詞who,what,which,when,where,whether,how后可接不定式構(gòu)成不定式短語，在句中作主語、賓語、表 語等。如：
①When to leave for London has not been decided yet. （不定式在句子中做主語）
②Mr. Smith didn't know whether to leave or stay there. （不定式在句子中做賓語）
③I asked Professor Xu how to learn English well. （不定式在句子中做間接賓語）
④The question was where to get the medicine needed. （不定式在句子中表語）
以上例句中疑問詞＋不定式部分，均可轉(zhuǎn)換為相應(yīng)的從句形式。如：①When we shall leave…③…how I
could learn…
經(jīng)常在這種結(jié)構(gòu)中使用的動(dòng)詞有：consider,decide,discover,explain,find out,forget,hear,know,lea rn,observe,understand,wonder等。
語法功能
一、作主語
動(dòng)詞不定式作主語時(shí)，句子的謂語動(dòng)詞常用單數(shù)，其位置有以下兩種：
(1)把不定式置于句首。如：
To get there by bike will take us half an hour.
(2)用it作形式主語，把真正的主語不定式置于句后，常用于下列句式中。如：
①It＋be＋名詞＋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＋形容詞＋for sb＋to do
It is difficult for us to finish writing the compositionin a quarter of an hour.
④It＋be＋形容詞＋of sb＋to do
It is stupid of you to write down everything the teachersays.
⑤It seems(appears)＋形容詞＋to do
It seemed impossible to save money.
在句型③中，常用表示客觀情況的形容詞，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 表示贊揚(yáng)或批評(píng)的詞。在不定式前的sb，可看作其邏輯主語。這一句式有時(shí)相當(dāng)于Sb is＋形容詞＋to do句式 ，如：It'skind of you to help me with my English.=You are kind to helpme with my English.
(3)舉例
1） It's easy (for me) to do that.我做這事太容易了
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.
聽到你的聲音真高興。
It's necessary for you to lock the car when you do not use it.
當(dāng)你不用車的時(shí)候，鎖車是有必要的。
2) It's very kind of him to help us. 他幫助我們，他真好。
Kind, nice, stupid, rude, clever, foolish, thoughtful, thoughtless, brave, considerate(考慮周到的), silly, selfish(自私的)
例句:
It was silly of us to believe him. 我們真愚蠢，竟然相信了他。
It seemed selfish of him not to give them anything. 他不給他們?nèi)魏螙|西，這顯得太自私了。
注意：1) 其他系動(dòng)詞如，look，appear等也可用于此句型
2) 不定式作為句子成分時(shí)，動(dòng)詞用單數(shù)形式。
3) 當(dāng)不定式作主語的句子中又有一個(gè)不定式作表語時(shí)，不能用It is… to…的句型
(對(duì))To see is to believe. 百聞不如一見。
(錯(cuò))It is to believe to see.
二、作賓語
1) 動(dòng)詞+ 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.
舉例：
The driver failed to see the other car in time.
司機(jī)沒能及時(shí)看見另一輛車。
I happen to know the answer to your question.
我碰巧知道你那道問題的答案。
2）動(dòng)詞+不定式 ；動(dòng)詞+賓語+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜歡每件東西都保持整潔。
I like you to keep everything tidy. 我喜歡你使每件東西都保持整潔。
I want to speak to Tom. 我想和湯姆談話。
I want you to speak to Tom. 我想讓你和湯姆談話。
3） 動(dòng)詞+疑問詞+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please show us how to do that. 請(qǐng)演示給我們?nèi)绾稳プ觥?div style="height:15px;">
There are so many kinds of tape-recorders on sale that I can't make up my mind which to buy.有這么多的錄音機(jī)，我都拿不定主意買哪一種。
The question is how to put it into practice.
如：agree,ask,aim,arrange,choose,decide,demand,expect,fail ,help,hope,lean,long,manage,offer,plan,prepare,
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)當(dāng)復(fù)合賓語中的賓語是不定式時(shí)，先用形式賓語it代替不定式，把不定式置于補(bǔ)語之后，即：主語＋動(dòng) 詞＋it＋補(bǔ)語＋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.
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
a. Father will not allow us to play on the street.
