什么叫介词英语
英语介词是表示词与词、词与句关系的词。
介词是一种用来表示词与词，词与句之间的关系的词。在句中不能单独作句字成分。介词后面一般有名词代词或相当于名词的其他词类，短语或从句作它的宾语。介词和它的宾语构成介词词组，在句中作状语，表语，补语或介词宾语。
分类：
1、常用简单介词：
about, across, against, among, after, at, behind, besides, beyond, by, concerning, beneath, between, despite, except, during, down, for, from, past, than,under,until等。
2、合成介词：
inside,outside,onto,out of,within等。
3、短语介词：
according to, ahead of,along with,as for, because of,be means of, due to, in spite of,on behalf of,owing to, with regard to 等。
重要介词的重要用法：
（1）from：此介词表示“to”相反的方向。
He came from London.
He went to London.
二词常搭配使用"from... to.."
We studied English from morning to afternoon.
He'll start from Beijing to Shanghai.
由from引导的惯用法：
from far 从远处。
from now/ then on 从现在/那时起。
from bad to worse 每况愈下。
from time to time（occasionally 时而）。
（2）out of：表示与"into"相反的语意。
He will be out of town.
I stepped out of the dark room.
out of+名词（=lack,to be without用完，用光）。
He went to the shop because he was out of paper.
out of date（= old-fashioned 过时的）。
The book has been out of date.
