表示词与词、词与句关系的词。
常用介词：on、at、in、、by、with等；
合成类介词：、、onto、out of、 等；
短语类介词： to、 of、 with等。
一、含义
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。
二、分类
1.常用简单介词：
, , , , , at, , , , by, , , , , , , down, for, from, past, than, , 等。
2.合成介词：
, , onto, out of, 等。
3.短语介词：
to, of, with, as for, of, be of, due to, in of, on of, to, with to 等。
三、介词与“……的”之关系
在英语学习中，一遇到“……的”，大家就会立刻想到’s 所有格或者of。实际上，在很多情况下，“……的”必须借助于介词才能准确表达。
● 美国的冬天→ the in
● 停车场的入口→ the to the lot
● 穿过森林的小路→ the path the
● 鲁迅的著作→ the by Lu Xun
● 水中的月亮→ the moon in
● 历史的见证→ the to
● 对爱的渴望→ a for love
● 对我们不利的证据→ the us
● 阳光下的漫步→ a walk in the
● 追求名誉的女人→ a lady fame
● 两人之间的争论→ an the two
四、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 .
He went to .
二词常搭配使用“from... to...”
We from to .
He'll from to .
经典用法：
● 由于→ The girl is from fear.
● 免除→ are free from care. 流浪汉们总是无忧无虑。
● 分开→ The from each at the .
● 由……制成→ The red wine is made from . 红葡萄酒是由葡萄制成的。
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 每况愈下
from time to time( 时而)
习语：
She to me from time to time.
(2)out of：表示与"into"相反的语意。
He will be out of town.
I out of the dark room.
out of+ 名词 (= lack, to be 用完，用光)
He went to the shop he was out of .
out of date (= old- 过时的)
The book has been out of date.
out of work (= 失业的)
He be is out of work.
out of the (= 不可能的)
the hard work is out of the .
out of (= 毫无疑问的)
That he can do it well is out of .
out of (= not 失灵的)
Her is out of , so she can't to it.
(3)by：表示从旁经过或在……附近。
He by me .
He by the sea.
经典用法：
● 通过→This is the road by they came.
● 在……时候→The man by day and by .
● 由……所生→He has two sons by her wife.
● 抓住→She her by his coat in the .
● 按……计算→The sell by the .
● 就(气质，特征)而言→He is an by (气质).
用于被动语意，导出动作执行者：
The was by the boy.
by + 具体时间：
They have by 8 o'.
by + 交通工具 (bus, , plan...)：
He to by air/.
by the end of + 时间名词：到……末为止
By the end of last year, they had 100 .
By the end of this term, they will have 100 .
by then：到那时
He will in 1999, by then he will .
by way of (= via)：经由，取道
They are to the by way of Hong Kong.
by the way：顺便问
By the way, do you know Mr. Li has gone?
by far：……得多(用于修饰比较级和*高级)
The book is by far the best on the .
by ：不小心，与on (故意地)语意相反
The was put into the by .
