一、概述
介词是英语中最活跃的词类之一。特别是一些常见介词与其它词语的搭配能表达各种不同的意思
介词不能在句中独立充当一个成分，而需要与名词或者相当名词的短语或者从句构成介词短语，在句中充当某一成分。介词后面的名词或者相当于名词的短语或者从句就是介词的宾语。
英语中介词一共有112个，但常见的介词有
at  about  above  across  after  against  as  before  beside  beyond  but  by  
except  for  from  in  into  like  of  off  on  out  over  round  since  than  through
till(until)  to  under  up  with without…
二、主要常见介词用法(16个)
AT
表示地点或场合
at the top (bottom, beginning, end, front, back) of
at the door (gate, entrance, window, table, desk)
at the bus stop (station, airport, post office, market, cinema, theatre)
at a bookstore (grocer’s hotel, restaurant)
at Mr Smith’s (Uncle Liu’s, at 400 , Beijing Road)
at home (school, college, church, Beijing University)
at breakfast (lunch, dinner)
at an evening party (a meeting, a wedding)
表示某一时刻，时间，时期等
at one o’clock (daybreak, nightfall, noon, midnight, dawn)
at Christmas (the beginning of September, the end of the next year)
at present (that time, the same time, that moment, the present moment)
at times  有时   at your age   在你的年龄       at all times  永远
at first   起先   at the present stage  现阶段      at last      最后
at the weekend  在周末  at hand      不远　　　 at fifteen = at the age of fifteen
at once   马上   all at once   　突然,马上
3.  表示价格，速度，温度，高度，比率等．
at that price (a good price, a lower price)　
at $ 10 a yard,   at one yuan for two catties
at a special discount       按特别折扣
at no cost               不花钱, 免费
at a speed of 400 kms/hr    以一小时400公里的速度
at top speed (a rapid rate)   最快速度(快速)
at an altitude of 10,000 metres    以一万米高度
at 1000 C     摄氏100度      at 800 F    华氏８０度　　　at zero     零度
4.  表示其它情况或用于某些成语及短语．
at a different angle    以不同的角度       at a loss        不知所措
at my expense       由我出钱　　　　　　  at any rate      不管怎样
at a distance     从远处,有一定距离  at most (least, best, worst) 至多(至少,最好,最坏)
at will 　　         任意   　　　　    at the top of one’s voice    高声地
at war    　　     在打仗    　　　　 at peace　　　　　　处于和平之中
at work　　　　　　在工作　　　　　　at play　　　　　　在游玩
at large　　　　　　逍遥法外　　　　　　at length　　　　　　　　最后,详细地,充分地
at sea　　　　　　茫然,不知所措　　　　at one’s service   　　听候吩咐
at the age of　　　　在…岁的时候
at the earliest(latest)   至早(至迟)　　　　at the risk of　　　　冒…的危险
at the same time　　　　同时　　　　　　　　at (the) worst  　　 在最坏的情况下
aim at 　　　　瞄准　　　　　　glance at　　　　看　　　　　　　　gaze at　　　　凝视
smile at　　　　微笑　　　　　　laugh at　　　　笑　　　　　　　　stare at　　　　凝视
wonder at　　　　对…感到吃惊　　　　　　　　be surprised at　　　　对.. 感到惊讶　　
be disappointed at　　对…感到失望　　　　　　be pleased (glad, delighted) at  对…感到高兴
be good (poor, quick, slow) at 　　　　　　be angry at　　　　　　对…生气

about
1.关于,对于,有关
I read about it in the paper.
What did you say about this question?
2.在…周围, 四面,附近等.
Everything about me was so beautiful.
There are a lot of trees and flowers about the grey house.
3.大约
There are about 30 students in his class.
He will be back about six o’clock.
4.用于某些成语.
What (How) about ．．．？　　　　　　　　你觉得．．．如何（怎样）？
be about to do sth.　　　　即将做．．．　　　　bring about　　　　引起, 造成,实现
come about　　　　　　　　发生,成为现实　　face(turn) about　　向后转,转过身来
go about　　　　　　　　着手　　　　　　　　leave …about　　　　　　到处乱扔　　　　　　
see about 　　　　　　考查,负责处理　　　　set about　　　　　　　　开始

against
1.表示反对关系,反对,违背,对着,以防.
be against sb.(sb.’s idea…)   反对某人的意见　　
Don’t do anything against the law.
We must fight against the enemy (pollution).
He helped me against my will.　　　　　　他违心地帮助了我.
They stored up grain against war.       他们储粮备战.
They ran against the wind.　　　　　　　　他们顶风跑.
2.表示位置关系,靠着,衬着,碰着.
She held the child tight against her body.　　　　他把孩子紧紧地搂在怀里.
They were dancing against the background of a rising sun.
他们以一轮冉冉升起的红日为背景跳着舞.

beyond
1.在…的那一边, 在更远处
The village is beyond that hill.
2.超出…范围(能力等)
beyond me expectations (my power)　　　　　　我没料到(我不能)
beyond compare (words, cure)　　　　　　　　无可比拟(无法用言语形容,不可救药)
beyond all things　　　　首先　　　　　　　　beyond (without) doubt　　无疑地,必定,当然
beyond hope　　　　没有希望　　　　　　　　beyond the sea(s)　　在国外,在海外,越过海
beyond (out of, above) one’s reach 　　　　　　够不着,为能力所不及　　
  
but
1.除开，除去（多和nothing, not anything, nobody, nowhere, who, all等连用）
      He took away everything but a broken chair.
      He is anything but a fool.
      No one but me saw him.
      Put it anywhere but on the floor.
      She looks anything but well.
      
2.常见句型结构：
　　　have no choice but to do sth.            除了．．．外，　别无选择
　　　do nothing but do sth.                 只能，只有做．．．
　　　There is nothing to do but do sth.
      but for       要不是．．．（句子多用虚拟语气）
　    But for the rain we should have had a pleasant journey.
      but that      若不是（引导从句）　　　
      He would have helped us but that he was short of money at the time.
作连词用
　　　cannot (help / choose) but do sth.         不能不，　只能
        He couldn’t but take the offer.
        We could not but be impressed by their warm concern.
      not only…but also                     不仅．．．而且．．．
　　　　This is not only possible but is necessary.
        Not only my mother was unhappy, but Marged, too.
      
by
1.表示空间, 在…旁
stand by me　　　　站在我旁边　　　　　　by the (side of a) river　　　　在河边
2.表示时间, 到某时
By July last year they had finished their plan.
I shall have retired by the time you leave.
3.到某时已出现的情况, 用于主-系-表结构.
I will be back by three.
Such planes should be ready for service by 1955.
4.表示方式手段 (通过,用,靠, 由于, 根据等)
We want to solve this problem by discussion with them.
Judging by the smell, the dish must be good.
Don’t judge a person by his looks (appearance).
5.取道, 经过
She returned to her daughter’s by the same route (road) .   从原路回到…
   I’ll come by Beijing.
6.被, 由 (常用于被动语态)
The sword is made by hand , not by machinery.
7.表示交通工具或通讯手段.
by bus (train, boat, lorry, tube, plane)　　　　　　　　　　　　by sea (water, air)
be letter (air, mail, telephone, telegram, post, e-mail)
8.与某些动词搭配,表示接触身体或某物的某一部分.
seize sb. by the hand　　　　　　　　hold sb. by the hand　　　　　　pull sb. by the sleeve
pat sb. by the shoulder　　　　　　hake sb. by the hand　　　　shake sb. by the arm
9.说明数量,程度, 尺寸等.
He is paid by the hour (the day, the week, the month, the piece).
  　　　　　　　　　　他是按小时(天, 星期, 月, 件)计酬的.
increase (decrease, reduce) by 10 per cent (by nearly two-thirds, by several times).
增加(减少)百分之十 (近三分之二, 几倍)
10.用于某些成语.
by accident (by chance)　　　　偶然　　　　　　by all means　　　　　　想一切办法,一定要
by oneself　　　　　　单独地, 独立地　　　　learn… by heart　　　　记熟
one by one , little by little, step by step　　　　一个一个地, 一点一点地, 一步一步地　　
by mistake　　　　　　　　  出于错误　　　　by no means　　　　　　绝不, 一点也不
day by day,  year by year   一天(年)一天(年)地
by any chance　　　　　　万一,  碰巧　　　　by the way　　　　　　顺便说一件事
by turns 　　　　　　　　轮流　　　　　　　　by the name of　　　　　　名叫
by choice　　　　　　　　出于自愿　　　　　　by the time　　　　　　到…的时候　　
side by side　　　　　　肩并肩          by way of　　　　作为,  取道,经由

for
1.为, 替, 给(表目地)
Don’t forget to post the letter for me.
They have on honour for the country.
We are sorry for you.
   He is going to get some materials for a new book.
   It’s a machine for making boxes.
   This is a good medicine for cold.
2. 因为, 出于 (表示原因)
Thank you for giving us so much help.
He was praised for stealing.
3. 对于
　 He has a talent for music.
   I am too old for the job.
4. 就．．．来说，　作为
　 He is tall for a boy of ten.
   She is young for her age.
   It’s quite warm for February.
5. 赞成，主张（常引导短语作表语）　
Are you for the plan, or against it ?　　
I am for going to the zoo.
6. 表示时间的长度或距离
I haven’t seen you for ages(for five years).
He followed me for some distance(500 metres).
7.常见的固定搭配：
　for all   尽管　　　　　　　  They harvested very little for all their effort.
  for certain,  for sure    肯定地 I don’t know for certain that he will come.
　for good    长期地           I am going away for good.
　for fear that 　（跟从句）唯恐，以防  
                              Shut the window for fear that it may rain.
for days (months, years)   一连好几天（月，年）
for ever 　　　永远
for fear of 　　唯恐，担心　　　　　　
for example（for instance）例如
for oneself   自己
for one thing… for another    一则．．．再则
for pleasure(fun) 　作为消遣（闹着玩的）　　
for sale     供出售
for …. purpose      为．．．目的　　　　　=for the purpose of
for the first (second) time      第一（二）次
for nothing 　　　　不要代价地，白白地
for the moment      一时间　（暂时）
for the time being   暂时
for the present     就现在来说
for hours (days)    一连好几个钟头（天．．．）
for one’s good     为．．．的好
for the sake of     看在．．．的份上 　　
take… for         以为是，　当作
so much for        就谈到这里
word for word      逐句逐字地
call for            look for   take … for granted      wait for
  long for          
if it were not for (had not been for),    要不是（用虚拟语气）
  but for              要不是

from
1.从，自
The students of our class from all parts of this province.
I will meet you in Beijing one week from today.
2.由
The wine is much from oranges.
3.免除，防治，使不做（某事）　
The heavy rain prevented us from finishing the work.
The shed can at least protect us from wind and rain.　
4.用于某些成语
from bad to worse       (情况)越来越糟,每况愈下
far from               远远不是　　　　He is far from angry. 他一点也不生气．　
from beginning (start) to end (finish)    自始自终，从头到尾
from morning till (to) night, from dawn to dark    从早到晚
from now (that day) on      从现在（那天）起
from time to time           不时地
(live) from hand to mouth    勉强糊口
from head to foot           从头到脚
apart from        除了　　The children hardly see anyone, apart from their parents.
from … to….             从．．．到．．．　
come from    　　 know from  　　  　　hear from　　　　  　　made from     judge from
keep …from    stop…. from     prevent …from    protect …from　save … from
tell… from