不定式在句子中可做主语、宾语、表语、定语、状语和宾语补语.

　　1)不定式做主语一般表示具体的某次动作.

　　【例如】

　　Tocompletethe30?storiedbuildinginoneyearwasquiteadifficulttask.

　　Todothatimpliestakingresponsibility.

　　当主语较长,谓语较短时,常用it做形式主语,而将不定式放到谓语的后面.

　　【例如】

　　Itisimportantformodernyoungpeopletomasteratleasttwoforeignlanguages.

　　It做形式主语,不定式放在谓语动词之后常用于下列结构中：

　　a)Itis＋形容词(easy,important,difficult,foolish,inconvenient,unnecessary,right,wrong...)＋(for/ofsb.)＋不定式

　　【例如】

　　ItisessentialtoreserveatableinadvanceofChristmasEve.

　　Itishardtoputmyhopessintoswords.

　　Itisnoteasytocatchfishwithyourhandsonly.

　　ItisimportantforusyoungpeopletolearnEnglishandmasterit.

　　b)Itis＋名词(apleasure,apity,apleasantthing,one'sdu?ty,anhonor,ashame,acrime,noeasyjob...)＋不定式

　　Itisasheerwasteoftimetoreadthatkindoftrash.

　　Itisapitytohavetogowithouther.

　　Itisagloriousdeathtodieforthepeople.

　　c)Ittakes(sb.)sometime(hours,months,days,alotoftime,patience...)＋不定式

　　IttakesmethreehourstolearnEnglisheachday.

　　Ittookthemhalfthenighttogethomeinthesnow.

　　2)不定式作表语不定式作表语常表示将来的动作,主语常常是表示意向、打算、计划的词,如wish,idea,task,purpose,duty,job等.

　　【例如】

　　Themostimportantthingforone'shealthistohaveplentyofexercise.

　　Mychiefpurposehasbeentopointoutthedifficultiesofthematter.

　　Thepurposeoftheorganizationistogreetallnewcomerstothecityandtoprovidethemwithanynecessaryinformation.

　　WhatIwantedwastogettheworkdoneasquicklyaspossible.

　　3)不定式作宾语不定式常在下列动词后面作宾语：

　　afford,agree,apply,arrange,ask,attempt,beg,begin,care,choose,claim,consent,demand,decide,desire,determine,

　　expect,fail,hope,hesitate,hate,intend,learn,like,manage,mean,neglect,offer,plan,preparepretend,promise,refuse,resolve,seek,tend,threaten,want等.

　　【例如】

　　Iliketogooutforwalksinthewarmsunshineinspring.

　　Mymotherhatestomovefromplacetoplace,forshefeelstired.Idecidetoworkhardandgetdoctor'sdegree.

　　Theroomisdesignedtobemystudy,butnowithastobeusedasabedroomforthechildren.

　　Shefailedtofinishtheassignmentintime,andshewasworriedaboutit.

　　ThereisamanatthereceptiondeskwhoseemsveryangryandIthinkhemeans()trouble.(CET-41997,1)

　　A)making

　　B)tomake

　　C)tohavemade

　　D)shavingsmade

　　mean后面一般加不定式,所以A和D可以排除.根据句意,他看起来非常生气,他想找麻烦,不定式的动作还没有实施,应用一般式,因此答案为B.不定式作宾语还常用在下面结构中；主语＋动词＋it＋形容词＋不定式.

　　【例如】

　　Wefounditimpossibletogeteverythingreadyintime.IthinkitimportanttolearnEnglishwellincollege.

　　使用这种句型的常见动词有：believe,consider,declare,feel,find,guess,imagine,prove,realize,suppose,think,等.

　　4)“wh?word＋不定式”结构不定式前加一个疑问代词(what,which,who,whom,whose)或疑问副词(where,when,how,why),以及连词whether构成特殊的不定式短语,其作用相当于一个从句,这样的不定式短语常在某些动词后面作宾语.

　　常见的可以接这种不定式短语的动词有：

　　know,see,decide,tell,ask,consider,discover,explain,findout,forget,guess,hear,imagine,inquire,learn,observe,

　　perceive,remember,think,un