动词不定式和动名词讲解.doc

动词不定式和动名词的句法功能比较： 一、作主语 不定式作主语 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： Itbe名词to do Its our duty to take good care of the old. It takes sb+some time+to do How long did it take you to finish the work? Itbe形容词for sbto do It is difficult for us to finish writing the compositionin a quarter of an hour. Itbe形容词of sbto do It is stupid of you to write down everything the teachersays. It seems(appears)形容词to do It seemed impossible to save money. 动名词作主语 Learning without practice is no good. 动名词作主语时，也常用It句式。如： Its +no good(no use,fun,a pleasure,a waste of time)+doing Its no good reading in dim light. Its no use sitting here waiting. There is no+doing There is no saying what will happen next. 在这一结构中，动名词后常带宾语，相当于Its impossible to结构。 动词不定式和动名词作主语的区别 不定式作主语经常表示具体动作，常与特定的动作执行者联系在一起；而动名词作主语经常表示抽象动 作，经常不与特定的动作执行者联系在一起。如： Its no good eating too much fat. Its no good for you to eat so much fat. 二、作宾语 不定式作宾语 只能跟不定式作宾语。如：agree,ask,aim,arrange,choose,decide,demand,expect,fail ,help,hope,lean,long,manage,offer,plan,prepare,pretend,promise,refuse,wish等，这些词大部分可接that引导的从句。 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. 介词but,except,besides+to do(do) 在这种句型中，如介词前有动词do，后面应接不带to的不定式；如无do，则接to不定式，即带do不带to， 带to不带do。如： The enemy soldiers had no choice but to give in. 动名词作宾语 只能接动名词作宾语，admit,appreciate,consider,delay,enjoy,finish,keep,imagine,mind,miss,practise,resist,risk,save,suggest,dont mind,give up,insist,on, put off等。如： I suggest spending our summer vacation in a seaside town. You must give up smoking, for it does too much harm toyour health. 动名词作介词的宾语 动名词前的介词有时可以省略，如：have difficulty(in)doinghave no trouble(in)doing,lose no ti me(in)doing,prevent/stop(from)doing,there is no use(in)doing等。 部分动词后面，既可接动词不定式，也可接动名词作宾语，意义不变。如：begin,continue,start,hat e,like,love,need,require,want等。 在need,require,want后接-ing形式，表示被动意义，也可接不定式，但要用被动形式，如：Your handwriting needs improving(tobe improved). 在下列情况下，一般要用不定式：hate,like,love前有would(should)时，如：Id like to have a cup of coffee. 当谓语动词begin,continue,start等是进行式时，如：Thestudents are starting to work on the difficult maths problem. begin,continue,start与know,understand等状态动词连用时，如：I soon began to understand what was happening. advise,allow,encourage,forbid,permit等动词后接动名词作宾语，或带不定式作宾语补足语。如： Our teachers dont permit our swimming in the lake. Our teachers dont permit us to swim in the lake. 部分动词后接不定式或动名词时，意义差别较大，应根据句子语境选择使用。 forget,remember,regret后接不定式，表示现在或未来的动作，接动名词表示动作已经发生。如： mean to do 打算做某事 Mean doing 意味着 try to do 设法尽力做某事 try doing 试着做某事 stop to do 停下一件事去做另一件事（不定式作目的状语） Stop doing 停止做某事 cant help doing 禁不住 cant help to do不能帮助干 go on to do 做不同的事或不同内容的事 go on doing 继续不停地做某事，指同一动作的继续 三 作宾语补足语 (1)常要求不定式作宾补的动词有：allow,ask,advise,beg,cause,drive（强迫），encourage,expect,forbid,force,get,would like(love,hate),order,permit,persuade,teach,tell,want,warn,wish等。如： Would you like me to give your regards to Mary? I want you to understand the whole passage clearly. (2)部分动词后常接to be形容词、名词短语等形式，有时to be可省略，如：believe,consider,discover,find(=consider),feel(=think),imagine,judge,know,prove,think,suppose,see(=understand),understa nd等。 We all believe John(to be)honest. I consider him(to be)one of the best biology teachers of No. 1 Middle School. 但当不定式是完成式时，to不能省略，如：We consider him tohave been foolish. (3)感觉动词和使役动词后用作宾补的不定式须省略to。 I didnt hear anyone say anything about it. They make the students do too much homework every day. 这种句式在变为被动语态时，to不能省略，如第句：Thestudents are made to do too much homework every day. (4)help,know后面的to可有可无。如： Would you please help me(to) fill in the taxform? Ive never known her(to)be late before.但：He was known to have been to France before. (5)部分短语动词后，常接不定式作宾补，如： You may depend on them to be there early. The Party calls on us to increase production and practise economy. 常这样用的短语动词有：ask for,care for,call on,count on,depend on,wait for,long for（渴望）， prepare for,wish for等。 四、不定式作状语 作目的状语，有时为了强调，不定式前可加in order或so as。如： Bob took down my telephone number so as(in order)not toforget it. 有时为强调目的状语可把in order to或不定式置于句首，但so as to不能这样用。在这种句式中不定式部 分可转换为so that,in order that,成为目的状语从句，如： 作结果状语 soas to;suchas to Im not so stupid(a fool) as to put it in writing.我不至于愚蠢到会把它写下来。 Im not such a stupid fool as to put it in writing. enoughto The speed is high enough for us to catch up with thefirst liner. only to Jane hurried back only to find her mother dying inthehospital. tooto Im too tired to stay up longer. 但在下列结构中，tooto并非是“太而不能”之意。如： 不定式短语还可作独立成分，用于句首、句中或句末。如： To tell the truth,the play was a great disappointment tome. 常见的短语有to be exact（确切地说），to begin with（首先），to do him justice（说句对他公道的 话），to be sure（真的）等等。 五、动词不定式、动名词的其它用法 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。 动词不定式的被动语态 有些动词后的动名词用主动形式，但表示被动意义。如： The bike needs repairing. If a thing is worth doing, it is worth doing well. 3在why引起的问句中，省略to。如： Why spend such a lot of money? Why no