1、动词不定式初三I want to go swimming.The police warned him not to park the car here.Its useful to learn English well.不定式的概念（一）定义及形式 不定式是指无人称和数的限制，在句中起名词、形容词 或副词作用的成分。虽然不能作句子的谓语，但它具有 动词的一些特征，如可以跟宾语、可以有状语修饰。不定式有两种形式,一种是带to的不定式，一种不带to,又被称为动词原形（二）不定式的特征1.及物动词的不定式形式可以有自己的宾语，I like to read detective stories.2.可以被
2、状语修饰，He asked me to say my name aloud.3.没有人称和数的变化,即不受主语的人称和单复数的限定或影响 She liked to play the piano when she was young.4.其否定形式是在不定式前面加not，The teacher has told me many times not to be late again.5.可用for或of结构引出不定式的逻辑主语 Its important for us to work hard./It s very nice of you to help me with my English.（注
3、意for和。作句型中的用法的不同）不定式的用法不定式的用法(一)作主语 不定式在句中做主语，相当于名词或代词所起的作用,谓语动词用单数,往往用it作形式主语,把不定式放在谓语后面。It is impossible for us to get there on time.It took us two hours to finish the job.（二）作宾语1.动词+不定式。如：He managed to escape from the fire.常用不定式作宾语的动词：want,hope,wish,need,promise,refuse,decide,learn,agree,choose等2
4、.动词+特殊疑问词+不定式，“特殊疑问同+不定式”相当于名同，作宾语。如：I dont know what to do.I cant decide when to go there.注意：不定式作宾语时，如果还带有宾语补足语，往往把不定式放在宾语补足语之后，用it作形式宾语，如：I find it necessary to learn a foreign language.（三）作宾语补足语1.动词+宾语+不定式。如:He warned me to be careful.可以用不定式做宾补的动词有：ask,tell,want,order,would like,invite,allow,warn
5、,wish,help,expect,encourage,enable等2.在动同 feel（一感），hear、listen to（二听），have、let、make（三让），notice、see、watch、observe、look at（五看）等后面的补足语中，不定式不带to,但改为被动语态后，必须带to They saw the boy fall off the tree./The boy was seen to fall off the tree.3.help后面作宾语补足语的不定式可带to，也可不带to。如：I often help him(to)clean the house.（四）
6、作定语 不定式作定语，修饰名词或代词，通常放在被修饰的词后，如：I have a lot of work to do.He is looking for a room to live in.注意：如果作定语的不定式是个短语，则要保留不定式短语中的副词或介词。如:I need a pen to write with.I have a little baby to look after.（五）作状语1.作目的状语：to,only to,in order to,so as to等 He ran so fast as to catch the first bus./He came to the sch
7、ool to see his son.2.作原因状语，往往跟在表示“高兴、愉快、生气、遗憾等情感形容词后，说明产生这种情感的原因。We were very excited to hear the news.Im sorry to have troubled you so much.3.作结果状语,常见于too.to.,enough.to的 句型中，表示事先没有预料到的，强调结果的岀乎预料，He hurried to the post office only to find it was closed.4.作条件状语 To turn to the left,you could find the
8、post office.如果向左拐，你就会发现邮局的。（六）作表语不定式作表语，表示主语的职业、职责或性质等 Our duty is to help the children to grow better.注意：当主语是不定式时，表语不能用doing,要用不定式 To see is to believe.不定式的逻辑主语不定式的逻辑主语不定式的逻辑主语有时是句子中某个名词或代词,有时用for或of引出，带有for/of sb.形式逻辑语的不定式称为不定式的复合结构，在句中可作主语、宾语、表语、定语、状语等。It is impossible for us to get there on time
9、.Its time for people to protect all the living things in the sea.省略省略to的不定式的不定式1.有些动词用在主动语态中，其后作宾语补足语的不定式不带to,这类动词有see,hear,watch,notice,feel make,have,1et等。Did you see anyone come into the room?Look at me draw the picture and then try learning.2.常用的省略to的不定式的结构 had better do sth 最好做某事 would rather d
10、o sth宁愿做某事 have nothing to do but do只能做某事 cant/couldnt help but do sth不得不做某事 Why not do sth?为什么不做某事?省略动词只保留省略动词只保留to的不定式的不定式为了避免与前面已岀现的动词重复，可以用to来代替不定式结构。I shall go if you wish me to.Will you join us in a walk?Ill be glad to.主动表示被动的不定式主动表示被动的不定式1.当 nice,easy,fit,hard,difficult,important,impossible,p
11、leasant,interesting等形容词容后跟不定式作状语，形容词说明不定式的特征或性质，而且句子的主语又是不定式的逻辑宾语时，常用不定式的主动形式表达被动意义。The question is easy to answer.Sometimes,business English is hard to understand.2.当不定式在名词后面作定语，不定式和被修饰的名词之间有动宾关系，且与作主语的名词或代词有主谓关系时，用不定式的主动形式表示被动意义。I have a lot of work to do today.He has three children to look after.
12、3.在there be.句型中，当不定式修饰名词作定语时,不定式用主动或被动，含义没有区别。There is a lot of homework to do/to be done.There are some clothes to wash/to be washed.课堂练习课堂练习1.Mary was heard just now.What happened?John was telling a joke.A.cry B.to cry C.laugh D.to laugh【解析】笞案：B考查动同不定式的用法。感官动词(feel,hear,see.watch等)和使役动词(make,let,h
13、ave等)的宾语补足语 都不带to,但是变为被动语态时要加上to,故选B.2.When you leave,please turn off the light energy A.save B.saving C.saved D.to save【解析】答案：D根据句意“当你离开时，关灯以便省能源”，注意原句中有谓语动词 please turn off，所以空中不能再填动词原形。根据句意，此处应用动词不定式做目的状语，故选D。3.So for the exchange program has brought many foreigners to China Chinese.A.study B.to study C.studying D.studied答案：B,考查动同不定式作目的状语的用法,由句意可知，学习汉语是这些外国人到中国的目的。动词不定式可作目的状语。故答案为B。5.Some children cant afford necessary stationaiy Lets donate our pocket money to them.A.buy B.buying C.to buy D.be bought 答案：C 动词afford后接另一动同时要用不定式形式，cant afford to do sth,表示没钱做某事,故答案为C。
