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/onat 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 /withHe 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 /amongCan 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 /exceptWe 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/ aboveThere 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 / toMongolia 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 /forsince 表示从过去某一时间以来for 表示一段时间I have been living here since 1982.（自1982年以来，我一直住在这里）I have been living here for 20 years.（我已经在这里住了20年了）9、of /fromThe desk is made of wood（看得出材料）Paper is made from wood.（看不出材料）The bread is made up of flour, sugar and milk.（由数种成分组成）10、by /onHe used to go to school by bike.（抽象概括）He came to school on this bike yesterday.（具体到哪一辆车）11、of /forIt’s kind of you to come to see me.（既说明不定式本身特点，又说明逻辑主语的品性） It’s important for you students to learn English well.（只说明不定式本身的特征）12、of /inThis is the most interesting of all the stories.（从个体的集体着眼）China has the largest population in the world.（从总体概括着眼）13、of /about /on表示“谈及，论述”Do you know of American singer John Denver?（涉及浅层关系）I have never heard about him.（表示谈论等深一步的关系）This book is on grammar.（以……为主要内容）14、through /past/acrossThe new railway runs through the small town.（穿过）He walked slowly past the tall building.（从旁边经过）Mary walked across the park to do some shopping.（强调从一边到另一边）15、by/ with通过……手段We write with a pen.（表示较具体的事物）There’s nothing to gain by waiting.（表示抽象）16、despite = in spite of（介词） / although（连词）despite 是介词，后面接名词或动名词，不能跟句子although是连词，后面要跟句子。

Although I was ill yesterday, I still went to school.Despite failure in the exam, I still have a chance to win in the term.17、as /likeas 1）用作介词时意思为“作为……，充当”如：She acted as an interpreter.2）用作连词时意思为“像……一样；当，由于”As it was cold, I didn’t go outside.like 用作介词，意思为像……一样John sings like a nightingale.18、by day（指白天）/ by the day（按日计算）I worked here by day and I am paid by the day.一、3. 表示地点时 at, in, on 的区别5.表方位的介词in, on, to, off的区别★ in 表示在境内.★ on 表示相邻或在边界上, 不在境内.★ to 表示在境外, 不接壤.★ off 表示在海面上靠近海岸的地方.Guangdong lies ____ the south of China and Fujian is _____ the east of it. Hainan is ____ the coast of the mainland.二表示时间介词1. at, in, on的区别1 The train leaves ___ 6:00pm, so I have to be at the station _____ 5:40 at the latest.A. at; untilB. for; afterC. at; byD. before;around2 The old man died ____ cold ____ a cold night.A. from; atB. of; inC. of; onD. for; during3 The railway was opened ____ traffic ____ April 4, 1985.A. to; onB. to; inC. by; onD. for; onin ,on, at的区别和用法1） at 表示在某一时刻或短暂的时间。