非限定动词基本知识点

非限定动词（Non-finite verb）
一、定义：非限定动词在句中不可单独用作谓语，不受主语的人称和数的限制；它在句中可以用作其他句子成分。

它包括三种：不定式（infinitive）、动名词（gerund）、分词（participles）。

二、功能：
三、形式：
☆现在分词的形式等于动名词，过去分词的形式即为动词的过去分词。

☆过去分词通常表示逻辑主语的动作已完成，或者与逻辑主语间是被动关系，如：
Gone from home so long, they couldn’t recognize the place at all. （表示动作已完成）
Some of them, born and brought up in villages, had never seen a train. （表示被动）
四、用法注意点：
1、不定式
①作宾补时，不带to的动词：感觉动词（feel，see，hear，watch，notice等）和使役动词（make，let，have），如：
We felt the house shake. I would have you know that I am ill. （不带to的不定式）
☆find与help之后，不定式可带to可不带to。

②“for+名（代）词+不定式”结构，如：
For a child to do that job isn’t suitable. It’s time for us to go.
☆在adj. + for sb. to do sth.和adj. + of sb. to sth.结构中，当形容词表示客观意义时，用for，如difficult，easy，impossible，important，hard等；当形容词表示主观意义时，用of，如nice, kind, good, bad, honest, stupid, silly, clever等。

比较下面两个句子：
It’s kind of you to say so. It’s easy for you to say so.
③“疑问词+不定式”结构：疑问词who, what, which, when, where, how后加不定式可构成一种特殊短语，在句中可用作主语、宾语、表语等。

如：
When to start has not been decided.（主语）I don’t know what to do.（宾语）
He didn’t know whether to go there or not.（宾语）The question was where to go.（表语）
④在but, except之前如有动词do，其后的不定式不用to；若之前的动词不是do，则不定式带to。

比较：
We now have nothing to do but/except wait. We now have no choice but/except to wait.
⑤疑问词why引导的省略句的不定式在当代英语中一般必须省去to，如：
Why talk so much about it? Why not try it again?
2、动名词
①在it is + no use/ no good/ fun后面加v-ing。

如：
It is no use crying. It is no good asking him for help. It’s great fun sailing a boat.
②在下列动词后面，只用v-ing形式：admit, avoid, consider, delay, deny, dislike, enjoy, escape, finish,
imagine, include, keep, mind, miss, practise, resist, risk, suggest, give up等。

在下列动词后面，常接不定式：agree, ask, claim, choose, decide, demand, desire, determine, expect, fail, hope, manage, offer, plan, pretend, promise, refuse, wish等。

既可接不定式又可接动名词的动词：begin, continue, endure, fear, forget, hate, help, intend, learn, like, love, mean, need, neglect, prefer, regret, remember, start, try, want等。

☆注意接不定式和动名词，意义不同的动词，如：try, regret, mean, forget, stop, go on, remember, can’t help等。

③介词+动名词结构，如：succeed in doing sth. , believe in doing sth. , object to doing sth. , insist on doing sth. , think of doing sth. , worry about doing sth. , accuse sb. of doing sth. , devote…to doing sth. , pay attention to doing sth. , prevent sb. from doing sth. , agree on doing sth. , aim at doing sth. , aware of doing sth. , busy in doing sth. , capable of doing sth. , equal to doing sth. , fond of doing sth. , guilty of doing sth.等。

④有些时候，动名词以主动态表示被动意思。

如：
Our classroom needs cleaning. = needs to be cleaned.
If a thing is worth doing, it is worth doing well.
3、现在分词
①现在分词用作状语时，可置于句首，也可置于句末。

如：
He went out shutting the door behind him.
Seeing that it was raining, Tom took his umbrella.
②有些现在分词用来表示说话人对所说的话的一种态度，它们已变成固定词组，可以看作一种句子的独立成分。

如：
generally speaking 一般来说judging from…从…来判断talking of …说到…
allowing for …考虑到…considering…考虑到…
counting…算上…supposing…假定…
③现在分词的形式等于动名词，但作定语时，现在分词表示其所修饰的名词的动作，即，现在分词与其所修饰的名词在逻辑上具有主谓关系。

动名词则表示其修饰的名词的性质，二者逻辑上无主谓关系。

如：a sleeping child（现在分词）和a sleeping car（动名词）的区别。

4、过去分词
①一般来说，现在分词表示主动意义，过去分词表示被动意义。

如：
A young man writing novels died yesterday.
The novel written by him is quite popular with teenagers.
②现在分词所表示的动作尚未完成，过去分词所表示的动作则多已完成。

如：developing countries（发展中国家）和developed countries（发达国家）。

③过去分词与现在分词的被动态有时意义相同，但有时有区别。

如：
I saw the laptop being connected to the net. （我看到那台笔记本正被连入网络。

）
I saw the laptop connected to the net. （我看到那台笔记本被连入了网络。

）。