根据介词的构成分类：
·简单介词：at在...处/时，in在...里面，on在...上面
·合成介词：inside在...里面，onto朝/向...，into进入...
·双重介词：from behind从...后面，from among从...中间，until after直到...后
·短语介词：at the back of在...后面，in front of在...前面
·V-ing形式介词:including包括，considering考虑到，regarding关于
根据介词的意义分类：
·时间介词：about大约，for长达，by到...为止，since自从，during在...期间
·地点/方位介词：around在...周围，over在...上方，close to靠近，out of从...出来
·手段/施动者介词：like像，with用，in用，by使用，被...
·其他含义介词：of具有...的性质，instead of而不是，except除...外
介词短语：
介词的宾语：介词不能单独做句子成分，其后需有名词或相当于名词的词，短语或句子做宾语。
·I live near the city center（名词短语作介词的宾语）
·i'm afraid I don't agree with you（代词作介词宾语）
·Four from ten leaves six（数词作介宾）
·We're going to talk about when we'll leave（从句作介宾）
·Thanks very much for your coming（Ving形式作介宾）
·Could you give me some advice on how to learn English well？（“疑问词+不定式”作介宾）
介词短语的句法功能：
·作表语：My parents are at work now / They are from Canada
·作补足语：When she woke up，she found herself in hospital / He is considered as the greatest leader in China
·作定语：Have you got the answers to these questions？
·作状语：Can you sing this song in English？方式状语/Because of the traffic jam,I was late for class 原因状语/ I will see you at your office 地点状语/The final examinations take place in early June时间状语/He was too careless，In a word，he made too many mistakes句子状语
介词的位置：介词一般放在宾语前，但下列情况通常后置
·介词的宾语为疑问代词时：What are you interested in? /Whom did he talk to just now?
·介词出现在感叹句中时：What great trouble we are in！
·介词的宾语为关系代词that时：All that I am interested in is traveling
·某些定语从句中：This is the school in which we studied / The children who you are going to look after are under six
·被动句中作谓语的短语动词中的介词：The sick and the old here are taken good care of /All these things will be talked about next time
·其他情况：She is a nice girl to work with / The music is worth listening to once again
介词的用法：
·表时间：
1，at，具体时刻前，把某一段时间看作某一刻，在节假日前
at 7：30在7点半 / at Christmas在圣诞节/ at noon在中午/at midnight在午夜/at that time在那时/at breakfast吃早餐/at first首先/at last最后/at the end of在...最后/at the end最终/at the moment此刻/at present目前
2，on，具体的日期，星期几或节日等，具体某一天或某一天的早晨，中午或晚上等
On Monday在星期一/on the following day在第二天/one May the first在五月一日/on New Year’s Day在元旦/on Monday morning在星期一早晨/on the weekend在周末/on a rainy day在一个雨天/on a cold day在一个冷天/on the following evening在第二天晚上/on the morning of April the first在四月一日上午
3，in，时间较长时，还可表将来或从现在算起的一段时间之后
In the evening在晚上/ in August在八月/in 2020/in spring/ in one’s life/in the 21st century in three days三天后/in the future将来/in the daytime在白天
4, during 除了具有in表示时间段的功能外，还可指某一项活动过程中
During the night/during the fire在发生火灾期间/during the meeting/during the meal
5, for+时间段表“延续...之久”常跟现在完成时/过去时/将来时一起使用
They have lived in China for two years/They lived in China for two years/They will live in China for two years
6,since+时间点表“自从...以来”表示自过去某时延续至今的一段时间，常用现在完成时
She has worked here since 1999/I haven't written home since National Day/We haven't seen each other since three years ago
7, before和by，都可表示“在...之前”，但by含有“最晚不迟于...，到...为止”的意思，如by后是将来的时间，则句子用将来时或将来完成时；若是过去的时间，则句子用过去完成时。
I will be back before supper time /Supper will be ready by 6：00 / This factory had produced more than one million cars by the end of last year
·表地点，方位的介词
1，on指与物体表面接触，在某物的表面上
There is a apple on the tree树上长出了一个苹果/there is a picture on the wall
2，in暗示占去了某物的一部分
There is a bird in the tree树上飞来一只鸟/he is lying in bed他正躺在床上
3，over强调在某一物体的正上方
The brige over the river河上的桥
4，above强调在上方但不一定是正上方，也可指温度，海拔等刻度
The plane flew above the clouds
5，under强调正下方，是over的反义词
A cat is sitting under your chair
6，below强调在下方，不一定是正下方，也可指温度，海拔等刻度
It is 50 meters below the sea level
7，in front of和in the front of，前者表某以空间外部的前面，后者表某空间内部的前面
There is a tree in front of my classroom教室前面有颗树(教室外)/ There is a tree in the front of my classroom教师前面有棵树(教室内)
8，between和among前者指两者之间，可指3个或以上的人/物的每两个之间；后者用于3个或以上的人/物之间或笼统的一群人或物中
The house stands between two farms房子位于两个农场之间/The house stands among farms房子位于农场之间
9,across，through，past，over，across强调穿过某一平面，through强调从某一空间内通过，past强调从某事物的一旁经过，over强调从一边到另一边或越过某一高度
Be careful while walking across the street
Walk through the gate，and you'll see the rest room
Our bus drove past the Great Hall of the People
I saw an old man walking over the street
The dog jumped over the fence and ran away
10,表示“用...”的介词，with多指用工具或身体的某一部位/器官；by表示使用的方法/手段；in指使用语言/工具的具体类型，材料等
What can i cut the cake with？
You can see it with your own eyes
Why don't we go there by car instead？
He made the speech in Englihs
Don't write it in pencil. Write it in ink,please.
注意：“by+交通工具的可数名词单数”，其中名词前不加任何修饰语，如by bike，by bus；“take/catch/in/on+冠词/名词所有格/形容词性物主代词等+佳通工具的可数名词单数”如 take a bus/take a train/on a bus/in Rosa's car等；“by+交通线路的名词”其中名词为可数名词单数或不可数名词，且前无任何修饰语，如by air，by sea
·表示“除...”的介词
1，一般情况，but和except通用，表示“除...外”，其后的宾语时被排除在外的
Nobody but/except John knows the city well只有约翰非常了解这座城市
Who but/except you should be blamed for the mistake？
2，except for“除了...之外”，但对某种基本情况进行具体的，细节方面的修正，其后所接的词同句子的主语不是同类的，指从整体中除去一个细节/方面
The street in the early morning is very quiet except for a few cars
The bus is empty except for two passengers除去两名乘客公车就空了
3，besides“除...之外还...”
Many students have been to the Great Wall besides me包括我很多学生也去了长城
·介词by的常见用法
1，“介词by+Ving形式”在句子中作方式状语，意为”以，靠，借助，通过”，表示用某种方法或手段来达到某种预期的目的
You can get a taxi by calling this number
2，介词by表示位置，“在...旁边，靠近...”表示交通方式，意为“乘坐”，表时间意为“在...以前，不迟于”，用于被动语态“被...”
They are playing by the sea靠近海边