何时用不定式何时用分词和动名词I .动名词和不定式做主语的相同点1. 不定式短语和动名词做主语时，常常为了保持句子的平衡，用it来做形式主语，如:It is not easy to learn English well.It is no use asking him for help.2. 如果主语用了不定式,表语和宾语也要用不定式;主语用了动名词，表语和宾语也要用动名词，这在英语中称 为对称性,如：To see is to believe, = Seeing is believing, (I 艮见为实)(85)It is better to stay home than _A__ out.A. to go B. going C. go D. goneII ,动名词和不定式做主语的不同点1. 不定式做主语常表示具体的某一动作;表示泛指或一般的抽象的概念时，多用动名词，如：(92) _B_ is a good form of exercise for both young and old.A. The walk B. Walking C. To walk D. Walk2. 在”There/It +be+ no use(good/help/need)^之后常用动名词做主语，而少用不定式，如：It /There is no use crying over the split milk.It /There is no help taking this medicine.★但是如果该句型中用了 for引出不定式的逻辑主语，就只能用不定式，如:(93) There is no good for us to do that exercise.3. 不定式可以和when，where，how，what，whether等连用，在句子中做主语，宾语和表语，而动名词则不能，如：How to solve the problem is a hot potato.Where to put the box seems hard to decide.Whether to do it hasn’t been decided.What to do next is up to you.时态、语态及其基本用法A. 不定式1. 不定式的时态、语态有三种形式：①一般式，^口，to write / to be written :②进行式，如，to be writing / to have been writing;③完成式，如，to have written / to have been written。
2. 基本用法① 不定式的一般式，表示的动作与谓语动词表示的动作同时发生，有时也发生在谓语动词表示的动作之后如：He seems to know this.(=It seems that he knows this.)I hope to see you again.(=I hope that I’ll see you again.)He doesn’t like to be laughed at. (=He doesn’t like that he is being laughed at.)② 不定式的进行式，表示不定式的动作正在进行，与谓语动词表示的动作同时发生如：When the mother went into the room, the boy pretended to be sleeping. (=... , the boy pretended that he was sleeping .)I heard the English song being sung by him. (=I heard that the English song was being sung by him.)③ .不定式的完成式，表示的动作发生在谓语动词表示的动作之前。
如：I am sorry to have kept you waiting so long. (= I am sorry that I kept you waiting so long.)Having been well written，the book was translated into many languages. (=Because it had been well written, ...)B. 分词1. 只有现在分词才有时态和语态形式的变化现在分词的时态、语态有两种形式：①一般式，如，doing / being done;② 完成式，如，having done / having been done2. 基本用法① 现在分词的一般式，表示的动作与谓语动词表示的动作同时发生，或在谓语动词表示的动作之前发生如：The boys and girls went to school, singing and dancing all along the way .They all jumped with joy ,hearing the good news.The girl could not help crying ,being criticized in the public.② 现在分词的完成式，表示的动作在谓语动词表示的动作之前已发生，常用作时间状语或原因状语。
如：Having done the work very well ,he was praised by the teacher.Having been shot by a bullet, the man fell down dead.C.动名词1. 动名词的时态、语态有两种形式:①一般式，如，writing / being written ;②完成式，如，having written / having been written2. 基本用法① 动名词的一般式不表示动作正在进行，但作具有状语性质的宾语时，动名词一般式表示的动作与谓语动 词的动作同时发生如：The teacher is busy collecting the students’ exam papers.② 动名词的完成式在作具有状语性质的宾语时，表示的动作在谓语动词的动作之前已发生如：He was praised by the teacher for having done the work wonderfully.He felt so sorry for not having been given the chance to work in the company.三、 不定式、分词、动名词的词性特征和句法功能1. 不定式既有动词的一些特征，又具有名词、形容词、和副词的句法功能，因此，不定式在句中作：主语、 表语、宾语、宾语补足语、定语、状语、独立成分。
2. 分词即具有动词的一些特征，又具有形容词和副词的句法功能，因此，不定式在句中作：表语、宾语补 足语、定语、状语、独立成分3. 动名词，顾名思义，既有动词的一些特征，又具有名词的句法功能，因此，动名词在句中作：主语、表 语、宾语、定语、同位语四、 不定式、分词、动名词句法功能用法的比较1. 从上面不定式、分词、动名词的词性特征和句法功能中，我们不难看出它们在句子中的作用既有较多的 共性，又有稍微的差异：a. 相同的句法功能：①不定式、分词都能作：表语、定语、宾语补足语、状语、独立成分；②不定式、动 名词都能作：主语、表语、宾语：③不定式、分词、动名词都能作：表语、定语b. 不同的句法功能：不定式可作：同位语如：That was her desire, to go to America for further study after finishing middle school.2. 正确运用好不定式、分词、动名词⑴.不定式、分词、动名词作表语时的比较请看例句：① My job is to teach the students English.② My job is teaching the students English.③ My job is interesting.④ I am interested in English.辨析：A.①不定式与动名词作表语一般可以互换使用，在意义上没有多大差别，且其形式差异较大，很容 易把握，如上面例句的①②；②现在分词和动名词同形，在作表语时，学生不易识别。
分辨方法有三：a) 分词作表语说明主语的性质特征，回答how的问题;不定式和动名词作表语则说明主语的内容，回答what或 doing what 问题，如： My job is interesting.(=How is my job?) ; My job is teaching ( to teach ) the students English. (=What is my job?); b)动名词具有名词的句法功能，也能做主语，我们不妨把句中的表语转换成主 语，如果句子成立，则是动名词作表语，否则是现在分词作表语如： My job is teaching the studentsEnglish一Teaching the students English is my job.显然句子是成立的，原句中的teaching是动名词；c）分词 具有形容词的句法功能，那么，我们可以在作表语的分词前加very（extremely fairly ）等副词，如果句子成 立，则动词一ing形式作表语的是现在分词如上面例句：My job is interesting.可改为：My job is very interesting.显然句子是成立的，句中的interesting是现在分词。
B.确定用现在分词还是用过去分词作表语的方法有：现在分词作表语多表示主语所具有的某种特征；过去 分词作表语多表示主语所处的状态情感动词的v.-ing形式表示具有某种特征；情感动词的v.-ed形式多表 示引起某种情感一般地说，事物具有某种特征，而人才具有某种情感，因此，分词作表语的句式可归纳 为：a） Sb. + be + v-ed ; b） Sth. + be + v-ing.如：a. I am very excited ; b. The news is very exciting.但有一个词例外，那就是missing例如“那个男孩不见了”，我们不能说“The boy is missed .”，而是“The boy is missing.”⑵.不定式、分词、动名词作定语时的比较A. 作前置定语现在分词、过去分词、动名词可以作前置定语，而不定式不能作前置定语如：① a developing country , a developed country ; boiling water，boiled water ; ②building materials , a swimming pool ; the sleeping boy , the coming new year。
辨异的方法很简单：①现在分词具有主动、进行的特点，而过去分词则具有被动、完成的特点例如，a developing country=a country which is developing （发展中国家 ）； boiling water=water which is boiling（正在滚 开的水 ）;a developed country=a country which has developed发达国家 ）；boiled water=water which has been boiled（已滚开过的水）②现在分词和动名词同形，但作前置定语时，动名词表示所修饰的名词的用途，例 如， .building materials=materials for building; a swimming pool=a pool for swimming ； 而现在分词作前置定 语时，表示所修饰的名词正在进行的动作，两者是逻辑上的主谓关系例如，the sleeping boy=the boy who is sleeping ; the coming new year=the new year that is coming。
B. 作后置定语不定式、现在分词、过去分词都能作作后置定语，而动名词不作后置定语先看例句：① The problem to be discussed at the meeting is very important.② The problem discussed discussed at the meeting is very important.③ The problem being discussed at the meeting is very important.辨析：上面例句分别用不定式、现在分词、过去分词作后置定语，是因为它们存在不同的情况：不定式作 定语，表示动作正要进行（未发生）；现在分词作定语，表示动作正在进行（正在发生）；过去分词作定语， 表示动作已完成（己发生）据此，我们可以把上面的例句还原为定语从句作定语的句子，这样学生就更容 易理解：① The problem to be discussed at the meeting is very important.=The problem （ which is ） to be discussed at the meeting is very important.② The problem discussed at the meeting is very important.^ The problem （which was ） discussed at the meeting is very important.③ The problem being discussed at the meeting is very important.^ The problem （which is ） being discussed at the meeting is very important.⑶.不定式、动名词做主语、宾语时的比较A. 做主语例句： ① To read English aloud in the morning is very practical.② Reading English aloud in the morning is very practical .为了保持句子的平衡，可用it作形式主语，所以上面例句可写成为：一It is practical to read English aloud in the morning .一It is practical reading English aloud in the morning .B. 作宾语例句： ① He wanted to help him out with his English.② He doesn’t like being laughed at.③ I enjoy singing English songs .辨析：①一般说来，不定式与动名词做主语可以互换，其意义没有多大的差别，但认真分析起来，它们之 间还是有一些差异的：a )不定式做主语，一般表示的是具体的情况，而动名词做主语，一般表示一般性的情况。
如：It is no use to ask him. He knows nothing about this matter.It is no use asking him. He is foolish.b.同样，不定式做宾语，一般表示的是具体的情况而动名词作宾语，一般表示的是习惯性的动作如：I like to sing and dance right now .I feel so pleased to know that our football team has won the match.He has a good voice. He likes singing English songs.② 不定式作宾语时：a) 通常用于及物动词 want, hope, wish, need, promise, plan, pretend, prepare, fail, determine等之后如：I want to be proud of you.Einstein once refused to speak on the radio for $1,000 a minute.b) 如果作宾语的不定式又有自己的补语，则须用先行词it作形式宾语，而将真正的宾语后置。
如：We think it necessary to study English well.We feel our it our duty to help him.c) 不定式一般不作介词的宾语，只有少数介词如，but, except等后面才行此时不定式可以带to,如果介词 but, except等的前面有实义动词do, does或did时，不定式不带to.如：In very cold winter weather a cold blooded creature has no choice but to lie down and sleep.Yesterday afternoon he did nothing but lie in bed sleeping.③ 有些及物动词后面只能接动名词作宾语，这样的及物动词不多，主要是:mind, admit, advise void, face, enjoy, finish, excuse, imagine, escape, include, keep, pardon, practice, risk, miss, stand(忍耐，忍受),deny, suggest, give up, put off, can’t help(禁不住)，set about, prevent, prevent sb. from, object to(反对)，insist on 等。
如：The boy insisted on going to Beijing with his father for a tour.The girl didn’t mind being left alone at home.④ 有些及物动词的宾语可用不定式，也有可用动名词，可分两种情况：a) 意义基本一样，如 like, love, hate, begin, start, continue, cease, attempt, afford, prefer, delay, omit, neglect, propose, 等如：Marx started working(=to work) hard to improve his English.The Einstein’s cold not afford to pay for ( =paying for) the education that young Albert needed.但是，如果begin与start本身为进行式时，后面要接不定式，不接动名词如：He is beginning to see his mistakes.b) 意义明显不同，主要有以下几个动词。
a) remember(forget, regret ) + to v.表示不定式的动作尚未发生remember(forget, regret ) + v.-ing 表示动名词的动作已发生试比较：Please remember to close the door when you leave.I regret to tell you that he will not come to the party.I remember meeting her somewhere before.(b) mean + to v.意为：打算 ;想要 ;有 的意图mean + v.-ing意为：意味着 ；意思是 ；就是 试比较：I didn’t mean to hurt your feeling.Learning well English does not mean just working hard in a class.(c) stop + to v,意为：停下来做谋事stop + v.-ing意为；停止做谋事试比较：They stopped to talk .(= stopped what they were doing in order to talk.)The students stopped talking when the teacher came into the classroom..(d) try + to v.意为：设法 ；想法 ；试图 try + v.-ing意为：试着 ;试试看试比较：Ever since he came to this school, he tried to work hard at all his subjects .She tried reading, but that could not make her forget all her trouble.(e) sth.want( need, require) + to be v.-ed 意为： 需要 ; 该 sth.want( need, require) + v.-ing意为：需要 ;该 (动名词的主动形式表示被动的含义)试比较：My watch needed to be repaired.The matter wants thinking over.(=to be thought over).Those young trees will require looking after(=to be looked after).⑷不定式、现在分词、过去分作宾语补足语时的比较A. 不定式作宾语补足语不定式作宾补是比较常用的句式，如：He asked me to help him with his English.The teacher encouraged us to make greater progress.但用不定式作宾补要注意下面两种情况：a) 不定式在感觉性动词，如see, hear, watch, notice, observe, feel, find等动词和使役动词 make, let, have之后 作宾补时，不定式的小品词to应省去。
如：I saw him go upstairs this morning .The teacher makes me write a composition a week.但上面的句子在改为被动语太时，to不能省去如：一 He was seen to go upstairs this morning.一 We are made to write a composition a week by the teacher.b) 某些及物动词，如 agree,employ,lead,refuse,decide,promise,excuse,insist,prevent,suggest, arrange 等之后不能 用不定式作其宾语补足语例如句子“我爸爸希望我将来当工程师”如果译文是“ My farther hopes me to be an engineer in the future.”,那么就错了正确的译文应是：“ My farther wishes (expects) me to be an engineer in the future.”； 或“ My farther hopes that I will be an engineer in the future.”B. 现在分词、过去分词作宾语补足语现在分词、过去分词作宾语补足语也是比较常用的句式，如：I heard him singing English songs.His English was poor .He could hardly make himself understood.学习小结：不定式、现在分词、过去分词都能作宾补，正确使用它们的方法是：首先确定它们与逻辑主语 即句子的宾语之间的关系，如果逻辑主语是它们动作的执行者，则用不定式或现在分词作宾补。
不定式表 示动作已完成，侧重工作的全过程，而现在分词表示动作正在进行；如果逻辑主语是它们动作的承受者， 则应用过去分词作宾补如：I often heard him sing English songs.I heard him singing English songs.I often heard English songs sung by him.⑸不定式、分词作状语时的比较A.不定式可修饰动词和形容词，表示原因、目的和结果a） 作修饰动词的原因状语如：The whole nation was in deep sorrow to learn of Premier Zhou Enlai’s death.He laughed to think of his stupid son.b） 作修饰动词的目的状语如：He went to buy an English dictionary in the bookstore.不定式作目的状语如果放在句子之前，则更为正式一些，语气也较重如：To be a teacher of the people, one must first be their pupil.c） 作修饰动词的结果状语。
不定式做结果状语，表示一种没有预料到的情况或结果，须放在被修饰动词的后面，如：He woke up to find that he was lying in the hospital.有时为了进一步加强预料不到的语气，在表示结果的不定式前还可加only,如：He went to see him only to find him out.d） 作修饰表语形容词的状语尤其要注意的是，此时作修饰表语形容词状语的不定式常用主动形式，表示 被动的含义如：My chair is comfortable to sit on.English is very difficult to learn well.B.分词可作多种状语，用法比较活跃a） 作时间状语（相当时间状语从句），如：Having finished his homework, he went to bed. （=After he had finished his homework, ...）（When） heated, ice will turn into water. （=When it is heated, ...）b） 作原因状语（相当原因状语从句），如：Being a Party member, I should take the lead. （=As I am a Party member, ...）Greatly inspired by the teacher’s words, he made up his mind to work even harder. （=Because he was greatly inspired by the teacher’s words, ...）c） 作方式、伴随或附加说明状语，如：Filled for the moment with extraordinary strength, he raised himself completely.He stood there waiting for a bus.Here for the four very difficult years they worked every moment that they could spare, weighing and boiling and measuring and calculating and thinking.d） 作条件状语（相当条件状语从句），如：Given some more time, she will do work even better. （= If she is given some more time, ...）Playing all day, you will waste your valuable time. （=If you play all day, ... ）e） 作结果状语，如：He dropped the glass, breaking it into pieces.有时在表示结果的现在分词之前还可加only表示预料之中的情况，如：He went to see him last night only finding him studying. He was always working hard!f） 作程度状语，如：The wind rose and it became freezing cold.8）作目的状语，如：Yesterday she went shopping with his classmates.h）作让步状语（相当于让步状语从句），如：Though warned of the danger, the children went on skating on the thin ice.（=Though they were warned of the danger, ．．．）要点提示：分词作状语，其逻辑主语就是句子的主语，如果分词表示的是主动、进行的动作，则用现在分 词作状语；如果分词表示的是被动、完成的动作或状态，则用过去分词作状语，如：Following the old man, he stepped into the room.Followed by the old man, he stepped into the room.Greatly interested ,I asked how he played these new works.⑹ 不定式、现在分词作独立成分时的比较A. 不定式作独立成分，表示不定式独立于句子的其他成分，是英语表达的一种方式，不常用，如：To tell you the truth, I am almost freezing.To be honest, I doke being left alone at home.B. 现在分词作独立成分，用来表示说话人的态度或看问题的角度，如：Generally speaking, boys are physically stronger than girls.Judging from his accent ,he must be an American.动词不定式可以表示目的，也可以表示将来的情况现在分词，是现在的情况，或者同时发生的情况过去分词，同理啦，表示的是已经发生的事情的状态在“go + -ing形式(运动名称)”和“ do some + -ing形式”这类固定短语中。
e.g We will go fishing if it doesn’t rain tomorrow.She did some shopping last Sunday.位于 would rather , had better , why (not)之后的不定式省略 TO； e.g You had better stay here until the police come.Why not go to the movie with us?need之后的非谓语动词形式的判定，主要考虑句子的主语同非谓语动词的关系：如句子的主语为非谓语动 词的逻辑主语，用不定式；如句子的主语为非谓语动词的逻辑宾语，用-ing形式e.g We need to water the flowers this afternoon.The flowers need watering this afternoon.。