一、构成
动词不定式是英语中动词的一种非谓语形式,即由小品词+动词原形构成,有两种形式,一种是不带to的不定式,另一种是带to的不定式。动词不定式(含动词不定式短语)有名词、形容词和副词的作用,在句子中除了不能充当谓语之外,可以充当其他任何句子成份。(注意:有一类谓语动词后只能接不带有to的不定式。)
1.使役性动词。如:have、let、make等,例:Qoit stop her let her to home.
2.感官动词。如:see、hear、notice、feel、taste、smell等,例:I heard somebody cry last night.
3.情态动词。如:can、may、must等。例:You can go first.
4.一些固定结构如。Could、do、nothing、but、had、better、would、rather……than等。例:Youid bctfer ask the teacher first.
5.Why和Why not引导的提建议句型:
Why not go there with me at once?
Why do you come here so early?
6.两个不定式被连接在一起时后不定式省去的:
It’s better to do than (to) say.
二、动词不定式的时态和语态
1.动词不定式一般式的主动语态“to+动词原形”除表示现在情况外,还可以表示将来。例:It’s very nice to see you.
2.动词不定式一般式的被动语态“to be +过去分词”,例:The old should be treated as a child.
3.动词不定式进行时态,如:“to be +doing”表示这个动作与句中谓语动词所表示的动作同时发生。例:He seems to be reading English.
4.动词不定式完成时态的被动语态,形式为“to have been+过去分词,表示这一动作发生在主语动作之前。例:She seemed to have unclerstood me.
5.动词不定式的完成式的被动语态形式为“to have been+过去分词”。例:It was very angry to have been treated as a child.
三、动词不定式的用法
1.作主语时,常用it作形式主语(it无词义)而将不定式尾后作真正主语。例:To learn English well is very usefullIt’s very usefull to learn English well. 注意:It’s + adj +for / of ++ to do sty中当形容词。如:carefull、clever、kind、good、right、wrong等词时或当sb与形容词有逻辑上的主谓关系时用of。例:It’s kind of you to help me.
2.作宾语、动词不定式常在:want、begin、stait、like、forget、ask、learn、decide、wish、hope、agree、refuse、fail、plan等的物动词后作宾语。例:He asked us to do that thing.
注意:动词不定式作宾语时,可用形式宾语it代替,不定式后移作真正宾语,其句型结构为:S+V+it+adj+(for sb) to do sth.例:I found it hessong to do that thing.
这类作谓语的动词有:think、make、find、feel等。
3.作表语:多用来表示将来的职业或要做的某件事。
例:Her job is to help the patients.
The most important thing is to funisb the book.
4.作定语,有两种情况
(1)被修饰成份在意义上是不定式所表动作的执行者,不定式的动词可以是积极动词,如果是及物动词就要带上宾语:He is the first one to come. And the last to leave.I saw him vide abike.
(2)被修饰成份在意义上是不定式的动作的承受者时,不定式的动词应是及物动词,如是不及物动词,其后应加相应的介词。例:He has no pencit to writle with.
总之,作定语的不定式与所修饰的名词在意义上有主谓关系或动宾关系,并且不定式放在被修饰的名词之后。
5.作状语
(1)作目的状语,表示做该动作的目的:
He came here to see his father.
(2)作原因状语:用在某些作表语的表情绪的形容词之后,说明产生这种情绪的原因,例:I’m sorry to hear that ……
常用的这类形容词有:sorry、happy、pleased、angry、clever、polite、foolish、wrong、saynised等。
(3)作结果状语
①only+不定式用来表示未预料到或令人沮丧的结果。例:I hurriecl to his house only to fird he was out.
②形副+enough+不定式,意为“只能……”来表示肯定的结果:He’s old enorgh to go to school.
③too+形副+不定式“有太……,都不能……”之意,有否定的意思:You ane too yourd to understand this.
④So……as+不定式结构,只表示结果。
He struck the snake so as to breack it’s back.
⑤有些动词不定式在不及物动词后或在及物动词的宾语后面,可作结果状语:They lived have to see the river.
(4)动作不定式也可跟在部分作表语的形容词后作状语,例:He is easy to get on with.
(5)部分动词后面用不定式和动名词作宾语均可,但意义上有差别,要区别对待,这样的动词有stop、rememhen、forget、help等。
(6)名词+短语“疑问句+不定式”这种结构,在句子中可以作主语、宾语或表语,相当于一个从句,例:
She asked her mother when to go home.
Her to do the work is easy to decide.
The most importary thing is how to get the jcb.
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