一个句子当中，已经存在一个主句有谓语动词，又没有连词的情况下，还有别的动词出现时，这些动词就充当了非谓语动词
考点一：疑问动词加不定式
常见的疑问词有who, which, when, where, how, what等。
疑问动词加不定式结构起名词作用，充当主语、宾语、表语
I’ve work with children before, so I know what to except in my job. 英语中有一些动词后可以跟一个
疑问词+不定式在句中做宾语，如tell, discuss, know, show, learn,decide,wonder, explain…
作简短回答或避免不必要的重复时，动词不定式常常省去to 后面的动词，只保留to。
A:Would you like to come to my party? B: Yes , I’d love to.省掉了to come to your party.
考点二：连词+doingsth/done
when we learn a foreign language, we remember more words.
When learninga foreign language, we remember more words.
睡觉的时候,你最好把音乐开小一点。 You’d better turn down the music when sleeping .
考点三：分词放在句首或在逗号后面作状语的形式
考点四：分词作后置状语 考点五: 分词作状语
考点六：分词的逻辑主语问题 I often hear him singingthis song.
Hearingthe news, hecouldn’t help crying.
考点七：在用分词短语作状语时，它逻辑上的主语必须要与句子主语一致，但有时它也可以有自己独立的逻辑上的主语，这种结构就是独立主格结构
独立结构可以表示伴随动作或情况，表示时间、原因、条件等
He rushed into the room, his face covered with sweat.(伴随情况)
The shower being over, we continued to march.(时间)
Somanystudentsbeingabsent,wedecidedtoputthe meeting off.(原因)
Weather permitting, we’ll have an outing tomorrow.(条件) 1. 分词的独立主格结构，当分词的逻辑主语不是主句的主语时，要给出它自己的主语，构成独立主格结构 The jobfinished, we went home.
相当于After the job was finished，we went home.
考点八：有些动词只跟动名词作宾语 如admit,avoid,finish,imagine,keep,mind 考点九：有些动词可跟动名词或不定式作宾语，但意义上有差别 如forget,remember,mean，regret，Stop，try等。
考点十：介词except/but之后接不定式时，介词前有do就接不带to的不定式，反之接带to的不定式
She has no choice but towaitfor the news.
The man can do everything but speakFrench.
动词want, need, require, deserve 等和形容词worth
后接V-ing形式的主动形式作宾语，表示被动关系。
如接不定式时，则必须用被动形式。 即need doing=need to be done
以下短语中to 为介词，接名词，代词或V-ing作宾语
get down to 开始认真（做某事）look forward to
stick to坚持turn to 翻到，求助于 see to 照顾，处理devote oneself to be used to (doing sth.)…