概述：非谓语动词指在句子中不是谓语的动词。它有不定式、动名词和分词三种形式，其中分词又分为现在分词和过去分词两种。用do表示to do, doing, doing, done。
非谓语动词在句中不能单独作谓语，但具有动词的其它功能，有逻辑主语，可带宾语或状语。否定形式是在前面加上not。如not to do, not doing, 注意不定式省略to时的表达had better not do, would rather not do, who not do.
动名词兼具名词的特征，可以充当主语、宾语、表语、定语；分词具有形容词和副词的特征，充当表语、定语、状语、补语。不定式具有名词、形容词和副词的特征，可以充当上述全部六种成分。
一、非谓语动词做主语
不定式和动名词可以作主语。
1，不定式和动名词有时可替换使用, 遵循前后一致原则。
To see is to believe. Seeing is believing.
注意此种一致不仅适用于主宾、主表一致，同时适用于and/or等连接的并列结构。
From your couch, you can ask these smart assistants to play your favorite music, check the weather, order pizza or _____ (track) flight. 此处应该填track原型，为省略to的不定式，与前面to play, (to) check, (to) order并列。
由 and, or等并列的两个或多个不定式，后面可省略to，但表对比时不能。
To live or to die, that is a question. To be or not to be ,that is a question.
2，疑问代词或疑问副词（why除外）加不定式可做名词使用，不可做状语。
How to keep healthy is of great importance in our life.
I don’t know what to do and where to go.
表示时间/条件/转折/让步的连词when/while/if/unless/although/even though/even if 加形容词、现在分词或过去分词时可作状语使用，相当于状语从句省略了主语加be动词，这种用法只用于主系表结构。
When finishing his work, he went home.
Though called a sea, the landlocked Caspian is actually the largest lake on Earth, covering more than four times the surface area of its closest rival in size, North America's Lake Superior. 虽然被称为海，内陆里海实际上是地球上最大的湖，相当于最接近它的大小的北美的苏必利尔湖面积的4倍多。
3, 非谓语动词做主语/宾语，常用it作形式主语/宾语，谓语动词用单数。同样主语从句的谓语动词也常用单数。
用作主语的不定式，它的逻辑主语可由介词of和for引出。当sb. + be + adj.符合句意时，介词用of。带of的句型与careless, clever, good, foolish, honest, kind, lazy, nice, right, silly, stupid, wise, wrong, careful , polite 等连用。
与for连用的形容词：possible，impossible，easy，hard，difficult，necessary.
It’s kind of you to help us.
It’s necessary for you to study hard .
4，be后接no fun, no good, no use，waste of time用动名词作后置主语。
There be no结构后用动名词。
It’s no good/use/fun smoking. There is no joking about it.
5，动名词的复合结构中，动名词的逻辑主语通常用名词’s或物主代词表示，如果不在句子开头，可以用名词的普通格、人称代词的宾格表示。在句首用所有格。
Jack’s giving him an answer was required.
The doctor does not mind me/my eating a little meat.
I can hardly imagine Peter sailing across the Atlantic Ocean in five days.
I can’t imagine you being unfair to anyone.
Imagine后常用动名词复合结构作宾语，注意与allow sb. to do sth., consider sb. to do sth.等不定式作宾补结构的不同。
6，不定式和动名词作主语的区别：
(1) 动名词作主语通常表示抽象或一般性动作；而不定式作主语表示具体或一次性动作。Lying is wrong. 抽象 To lie is wrong. 暗含特指某人
To live in Beijing is his ambition. 对某个人特指
Smoking is prohibited here．抽象
It is not very good for you to smoke so much．具体
I like swimming but I don’t like to swim today.
(2) 动名词作主语时，通常用以表示一件已知的事或经验。不定式短语通常用来表示一件未完成的事或目的。
Climbing mountains is interesting．经验
To finish the task will take a long time. 未完成
直击高考：
例1，In the classroom or out of it, (30) ______ (develop) curiosity is sure to be worthwhile. （2019上海宝山区二模）
在教室内外，培养好奇心肯定是有益的。
例2，______ to sunlight for too much time will do harm to one’s skin.
A. Exposed B. Having exposed C. Being exposed D. After being exposed（2002上海真卷） 过多晒太阳对皮肤有害。
比较：Exposed to sunlight for too much time, you will damage your skin.
例3，He says (28)_____ (catch) breaking the ban and having the bike seized would cause costly delays for workers. （2019上海崇明区一模）
二、非谓语动词做宾语
不定式和动名词可以作宾语。
1，只能用不定式作宾语的动词和短语：threaten, happen, afford, care, agree, offer, intend, arrange，plan，ask, beg, demand, promise, help, prepare, decide, refuse, dare, fear, choose, wish, hope, want, expect, fail, learn, know, pretend, manage, teach , get；set out, would like, be worthy to do/of doing, can not help but do等。
只接动名词作宾语的动词和短语：allow, permit, advise, consider, excuse, forgive, admit, mention, avoid, enjoy, imagine, delay, miss, stand, understand, mind, suggest, doubt, finish, keep, practice, resist, deny, forbid, appreciate, risk, escape, can't stand, set about, feel like, be worth, can’t help等。
在spend, be busy, have trouble/difficulty/problem, have a good/wonderful/hard time等后接 (in) + 动名词作宾语。
2, 在like, love, dislike, hate后动名词表抽象一般性动作，不定式表具体的一次性动作。 I like swimming but I don’t like to swim today.
3, need, require, want, deserve后动名词主动表被动，也可用被动不定式。be worth后主动表被动，但不可加不定式。
The flowers need watering/to be watered.
The car required repairing/to be repaired.
The novel is worth reading.
But you don’t need (25)________ (quit) sugar for healthy eating.
（2019上海嘉定区二模）
但你没必要为了健康饮食而放弃吃糖。
4, begin, start一般可以互换使用。主语是物时用不定式。
It began to rain.
The snow began to melt.
5, forget, remember, go on, mean, try, stop, regret接动名词和不定式意义不同。
forget/remember/regret doing指做过，to do指还没做
go on/stop继续/停止手头的事，to do继续/停下做别的事
mean doing 意味着，mean to do, 打算做
try doing试着做，try to do努力去做
I didn’t mean to do you any harm. 我并不想会害了你。
I regret to inform you that you are fired. 很遗憾地通知你你被解雇了。
6，would rather, had better, had rather, would sooner, rather than, can not but, can not help but, why…/why not… 后的不定式省to。而can not help doing结构不同。
不定式重复前面的动词时，留to省do。
You’d better not smoke here.
I can’t help but love you, even though I try not to.
If you don't want to do it, you don't need to.
but 和 except 后的不定式, 主句有 do必须省略 to。
I can do nothing but play online games.
dare, help后可带可不带to. Dare (to) do, help (to) do; help sb. (to) do
7, 动名词常做介词的宾语。to 作介词时，后接名词或动名词，不要误作不定式：object to，close to , lead to , refer to , point to , devote to , next to , belong to , be used to , look forward to, pay attention to等。
At the beginning of class, the noise of desks _____ could be heard outside the classroom.
A. being opened and closed
B. opened and closed
C. to be opened and closed
D. to open and close
答案是A，为动名词的被动语态的所有格形式作of的介词宾语。
直击高考：
例4，Modern methods (3) tracking polar bear populations have been employed only since the mid﹣1980s，and are expensive（4） （perform） consistently over a large area．（2019全国1卷）
仅仅自20世纪80年代中开始，追踪北极熊的现代方法才被利用，而且在大面积地区连续地实施费用昂贵。
例5，When Peter speaks in public, he always has trouble _______ the right things to say. A. thinking of B. to think of C. thought of D. think of .
（2012上海真卷）
当皮特在公众场合说话时，他总是想不起说什么。
例6，In its early years, the book set its sights on (24) _______ (satisfy) man's inborn curiosity about the natural world around him.
（2019上海宝山区二模）
在早期，这本书注重满足人对于身边的自然世界的天生的好奇心。
14期
