非谓语动词(the Non-Finite Verbs)---动词不定式知识总结非谓语动词是指在句子中不充当谓语的动词，主要包括不定式、动名词和分词(现在分词和过去分词)，即动词的非谓语形式。

非谓语动词除了不能独立作谓语外，可以承担句子的其他成分。

动词不定式既具有动词的一些特征，又具有名词、形容词和副词的句法功能。

Ⅰ、不定式的构成及变形：动词不定式是由不定式符号to+动词原形构成，在某些情况下to也可省略。

1. 不定式的一般式不定式的一般式表示的动作通常与谓语的动作同时或几乎同时发生，或是在它之后发生。

He appears to be very happy.（同时发生）To catch the train, we'd better hurry to the station by taxi.（to catch the train发生在hurry to the station之后）2. 不定式的进行式不定式的进行式表示正在进行的或与谓语动词同时发生的动作。

It happened to be raining when I got there.3. 不定式的完成式不定式的完成式表示的动作在谓语表示的动作之前发生。

I'm sorry to have lost your key.4. 不定式的完成进行式不定式的完成进行式表示的动作在谓语之前发生并且一直进行着。

He was said to have been living in London for twenty years.不定式的时态意义：He is said to be studying abroad.（不定式的进行式表示动作正在进行）He is said to have studied abroad.（不定式的完成式表示动作已经结束）5. 不定式的被动形式当不定式逻辑上的主语是这个不定式表示的动作的承受者时，不定式一般要用被动形式。

不定式的被动形式根据其与谓语动作发生的先后关系，有一般式和完成时两种。

一般式to be doneThese are the books to be given out to the students.完成式to have been doneThe novel is said to have been translated into many languages.6. 不定式的否定形式不定式的否定形式由not或never加不定式构成。

We decided not to go out because of the bad weather. 由于天气不好，我们决定不出去。

注意：谓语动词的否定和不定式的否定不同的意义I did not promise to wake him up. 我没有答应叫醒他。

I promised not to wake him up. 我答应了不叫醒他。

Ⅱ、不定式句法功能不定式可以作句子的主语、宾语、宾语补足语、表语、定语、状语等成分。

1.作主语To hear from you is nice.To be a good teacher is not easy.不定式作主语时，为了保持句子的平衡，往往以it作形式主语，而不定式置于谓语动词后。

It’s nice to hear from you.It’s not easy to be a good teacher.2.作宾语通常用于afford, agree, aim, arrange, ask, attempt, choose, continue, dare, decide, demand, desire, determine, expect, fail, hate, help, hesitate, hope, intend, learn, long, love, manage, mean, need, offer, plan, prefer, prepare, pretend, promise, prove, refuse, seek, threaten, trouble, wait, want, wish等动词后面。

I forgot to lock the door.Please remember to write to me.记忆口诀：三个希望两答应（hope，wish，want，agree，promise）一个要求莫拒绝（demand，refuse）设法学会做决定（manage，decide）不要假装在选择（pretend，choose）3.作表语My job is to pick up letters.He seemed to have heard nothing.4.作定语在the first, the second, the third, the last等之后通常接不定式作定语。

作定语时须放在被修饰的名词之后：He is always the first one to get up.I have a few words to say on this question.主动形式表被动含义：I have a book to read.It is easy to read.Have you anything to send?比较：Have you anything to be sent?She is the last to come.He is looking for a room to live in.There is nothing to worry about.5.作宾补通常用于advise, allow, ask, beg, cause, challenge, convince, enable, encourage, expect, forbid, force, instruct, invite, order, permit, persuade, recommend, remind, request, require, teach, tell, train, urge, want, warn等词后。

He ordered her to leave at once.He was forced to obey his mother’s order.6.作状语不定式作状语时通常表示目的，不定式用作目的状语有两个可能的位置，一是在句首，二是在句末。

一般说来，用于句首属于强调性用法，即强调动词的目的。

也可用于“be adj. to do”结构中作原因状语。

He got up early to catch the first bus.To finish the task on time, we have to work hard.I’m happy to hear the news.I’m surprised to see him here.only to...往往表示“意想不到”的结果；never to...可以接后续的结果。

so...as to..., such... as to..., enough to..., only to...以及too...to...等结构中的不定式也表结果：Her father disappeared, never to be heard again.I went to the bank only to find it was closed.Ⅲ、不定式和现在分词作状语的区别1.作目的状语。

不定式作目的状语，带有很强的目的性，有时可以把(in order) to do置于句首。

而现在分词作目的状语时，目的和伴随兼而有之。

多放于句末，与主句用逗号隔开。

(In order) to ensure success, we must make a complete and through plan.You should keep it a secret, trying to protect the plan.2.作结果状语。

不定式作结果状语表示意外的结果。

现在分词作状语表示自然的结果。

He returned home many years later, only to find that everything had changed.(意外的结果)It rained heavily last night, causing the river to rise.(自然的结果)Ⅳ、作独立成分to be honest, to begin with, to start with, to tell you the truth, to make a long story shortTo tell you the truth, I told a lie.To begin/start with, let’s sing a song.To make a long story short, he succeeded in passing the exam.Ⅴ、不定式特殊用法1.用it作形式主语动词不定式作主语时，如果主语太长，通常用it作形式主语，将真正的主语——动词不定式后置。

For us to learn English well is necessary.→It is necessary for us to learn English well.动词不定式作主语时，如果将句子变为疑问句，应使用it作形式主语。

To walk to the station takes twenty minutes.→Does it take twenty minutes to walk to the station?2.用it作形式宾语某些不能修饰人的形容词作宾语补足语时，不能用表示人的词作宾语，应用it作形式宾语，再用动词不定式的复合结构作真正的宾语；这类形容词常用的有necessary, easy, hard, common, possible及impossible 等。

父亲的猝死，使得他必须辍学。

误：His father’s sudden death made him necessary to leave school.正：His father’s sudden death made it necessary for him to leave school.3.动词不定式作定语时是否要介词动词不定式与被修饰的名词或代词构成动宾关系时，如果动词不定式的动词及不及物动词，或者该动词不定式本身有宾语，其后面应加上与之用法相应的介词。

We are looking for a room to live in.但被修饰的名词为place, time, way等时，则往往省略介词。