介词（preposition）
又称前置词，是一种虚词。介词不能单独做句子成分。介词后须接宾语，介词与其宾语构成介词短语。
一、介词从其构成来看可以分为：
1、简单介词（Simple prepositions）如：at ,by, for, in, from, since, through等；
2、复合介词（Compound prepositions）如：onto, out of, without, towards等；
3、短语介词（phrasal prepositions）如；because of, instead of, on account of, in spite of, in front of等；
4、二重介词（double prepositions）如：from behind, from under, till after等；
5、分词介词（participial prepositions），又可称动词介词（verbal prepositions）如：during, concerning, excepting, considering, past等。
二、常见介词的基本用法
1、 about 关于
Do you know something about Tom？
What about this coat？（……怎么样）
2、 after 在……之后
I’m going to see you after supper. Tom looked after his sick mother yesterday.（照看）
3、 across 横过
Can you swim across the river.
4、 against 反对
Are you for or against me?
Nothing could make me turn against my country.（背叛）
5、 along 沿着
We walked along the river bank.
6、 before 在……之前
I hope to get there before seven o’clock. It looks as though it will snow before long.（不久）
7、behind 在……后面
The sun is hidden behind the clouds.
8、by 到……时
We had learned ten English songs by the end of last term.
9、during 在……期间
Where are you going during the holiday. 10、except 除了
Everyone except you answered the question correctly.
11、for 为了
The students are studying hard for the people.
12、from 从
I come from Shanghai.
13、in 在……里 on 在……上面 under在……下面
There are two balls in/on/under the desk.
14、near 在……附近
We live near the park.
15、of ……的
Do you know the name of the winner.
16、over 在……正上方
There is a bridge over the river.
Tom goes over his English every day.（复习）
17、round/around 围绕
The students stand around the teacher.
18、to 朝……方向
Can you tell me the way to the cinema.
19、towards朝着
The car is traveling towards Beijing.
20、with 和……一起
me?
Would you like to go to the cinema with
学习这些介词时可以先记住它的汉语意思，然后参照例句来加深理解，并在今后的学习中加以灵活运用。
三、常用易混淆介词辨析
1、 after/ in 皆可表示时间在……之后，其区别为：
after 1）表示“在某点时间之后”，用于将来时。如：
We’ll go out for a walk after supper.
2）表示“一段时间之后”，用于过去时。如：
My mother came home after half an hour.
in表示“一段时间之后”，用于将来时。如：
We’ll go to school in two weeks.
2、at/in/on
at seven o’clock（具体某一时刻用at）
in April /in April,2002（具体某一月份或年份用in）
on April 5,2002/on the morning of Monday（具体某一天用on）
3、in /by /with
He writes in black ink.（用……材料）
The guard cut one boot open with a knife.（用……工具）
She always goes to school by bike.（用……手段）
4、between /among
Can you say the differences between the two words?（两者之间）
Premier Chou En-lai lives among the people for ever.（三者或三者以上）
5、besides /except
We have seen the crocodile besides Li Fang.（除……之外，还有）全部计算在内 We are all Chinese except Tom in our class.（除……之外）不计算在内
6、on /over/ above
There is a boat on the desk（在某物面上，与此物接触。）
There is a bridge over the river.（在某物正上方，与此物不接触，或横在某物上，或覆盖在某物上。）
She spread a cloth over the table.
He held his heads above his head. （“在……上”，强调“高于。”）
7、on/ in / to
Mongolia is on the north of china.（与中国接壤，不属于中国）
Japan is to the east of china.（不属于中国，且不接壤）
Taiwan is in the east of China.（台湾属于中国）
8、since /for
since 表示从过去某一时间以来
