介词是一种虚词，不能单独使用，数量虽然不多，但它与动词、形容词会形成很多搭配。
1、介词和种类
(1)简单介词，常用的有at,in,on,about,across,before,beside,for,to,without等。
(2)复合介词，如by means of,along with,because of,in front of,instead of等。
2、介词和其他词类的习惯搭配关系
(1)和动词的搭配，如agree with,ask for,belong to,break away from,care about等。
(2)和形容词的搭配，如afraid of,angry with,different from,good at
(3)和名词的搭配，如answer to,key to,reason for,cause of,visit to等.
3、介词短语可以有自己的修饰语，这种修饰语通常有right,just,badly,all,well,directly,completely等少数几个副词。如：
He came right after dinner.
He lives directly opposite the school.
4、某些介词的意义与用法举例
(1)at,on,in(表时间)
表示时间点用at,如at four o'clock,at midnight等;表示不确定的时间或短期假日也用at,如at that time,at Christmas等。
指某天用on,如on Monday,on the end of November,指某天的朝夕用on,如on Friday morning,on the afternoon of September lst等。
指长于或短于一天的时段用in,如in the afternoon,in February,in Summer,in 1999等。
(2)between,among(表位置)
between仅用于二者之间，但说三者或三者以上中的每两个之间的相互关系时，也用between,如
I'm sitting between Tom and Alice.
The village lies between three hills.
among用于三者或三者以上之间。如：
He is the best among the students.
(3)beside,besides
beside意为"在…旁边"，而besides意为"除…之外"。如：
He sat beside me.
What do you want besides this?
(4)in the tree,on the tree
in the tree指动物或人在树上，而on the tree指果实、树叶长在树上
(5)on the way,in the way,by the way,in this way
on the way指在路上in the way指挡道
by the way指顺便问一句in this way用这样的方法
(6)in the corner,at the corner
in the corner指在拐角内at the corner指在拐角外
(7)in the morning,on the morning
in the morning是一般说法on the morning特指某一天的早晨
(8)by bus,on the bus
by bus是一般说法on the bus特指乘某一辆车
