定义
介词又称前置词，是一种虚词，不能单独用作句子成分，通常用于名词或代词之前，表示其后词语与句中其他词语之间的关系。
结构分类
简单介词
由一个单词构成的介词
| 普通介词 | at, by, for, in, over, to, up | |
| 合成介词 | onto, into within, without | |
| 分词介词 | concerning, considering, including | Everybody here has influenza including myself. |
按照功能
| 时间介词 | It's a long time since breakfast. |
| 地点介词 | The moon was low in the sky. |
| 方式介词 | You can't get into the place without a pass. |
| 原因介词 | |
| 其他介词 |
双重介词
就是由两个简单的介词重叠石红而构成的。
from behind, from among, since before, until after.
A man stepped out from behind the wall.
I won't go home until after the exam.
He has known her since before the war.
介词短语
由两个或两个以上的词所组成的短语构成。一般短语的最后一个词是简单介词。
in case of(万一，以防), according to(根据，按照), because of(因为，由于), by means of(通过，借助),
in spite of(尽管，虽然), instead of(代替，没有做), on behalf of(为了什么，代表什么), with reference to(参考，参照).
Thoughts are expressed by means of words.
In spite of his efforts, he failed.
I keep an umbrella here in case of rain.
But things do not go according to plan.
Because of this we decided to leave early.
口诀
早，晚要用in
at黎明，午夜，点与分
年，月，季节，周，阳光，灯，影，衣帽in
将来时态in...以后，小处at大处in
有形with无形by，语言，单位，材料in
特征，方面与方式，心情成语管用in
介词at和to表方向
农场，值日on，关于，基础，靠，著论
工具，和，同，随，具有，原因with
海，陆，空，车，被by
over, under正上下，above, below则不然
beyond超出，无，不能，against靠着，对于反
before, after表一点，ago, later表一段
since以来during间，since时态多变换
Example
When they got home, Jane cooked their dinner in the microwave oven.
Would you mind not picking the flowers in the garden? They are for everyone's enjoyment.
Teachers live by selling knowledge.
Older parents often spend more time with their children.
Newman notes that Russia had a similar population density at the time.
Armed with a torch, the vicar went up into the clock tower to see what was going on.
In spite of his repeated cries, no one heard him.
A day may begin well enough, but suddenly everything seems to get out of control.
In response to renewed pleadings, Bruce stopped.
This puma must have been in the possession of a private collector and somehow managed to escape.
Some doctors were sent to the front where medical workers were in great need.
He is running with Tom against the wind along the path.
Early in the morning, we started off for the mountain village.