介词的用法一、介词的定义：介词为虚词，是一种用来表示词与词或者词与句之间的关系的词，在句中不能单独作句成分。
介词一定要有宾语，构成介词短语（即介宾结构），才能充当句子成分。
充当宾语的一般有名词、相当于名词的其它词、代词、形容词、短语或句子、短语或从句等，介词短语在句中常作定语、状语、表语和补足语。
二、介词的分类：1．简单介词：about, across, after, against, among, around, at, before, behind, below, beside, between, beyond, but, by, down, during, except, for, from, in, like, of, off, on, over, near, past, round, since, through, till, to, toward(s), under, until, up, with, per, via；2．合成介词：inside, into, onto, out of, outside, throughout, upon, within, without；3．短语介词：according to, along with, apart from, as for, as to, because of, by means of, in front of, instead of, on account of, on behalf of, owing to, due to, up to。
4．双重介词：如from behind, from among, until after, at about等。
三、介词的宾语1．名词：Let’s go for a walk along th e river. 咱们到江边散散步。
2．代词：He’s standing in front of me. 我站在我前面。
3．形容词：Her pronunciation is far from perfect. 她的语音远不是完美的。
【注意】有的形容词前可看作是省略了being。
4．动名词：He’s good at drawing.他善长绘画。
5．过去分词：I took it for granted that she was for England.我还以为她是英国的。
【注意】过去分词作介词宾语只限于take…for granted, regard…as, than expected后。
6．不定式：I had no choice but to lie down. 除了躺下外我别无选择。
She did nothing but cry.她只是哭。
【注意】介词后通常是不能用不定式作宾语，只有表示“除……外”的介词but能接不定式作宾语。
前面有行为动词do时，不定式不用to，否则要带to。
7．疑问词+不定式：I don’t know how to improve my English.我不知道如何提高我的英语水平。
8．副词：I didn’t know it until recently. 直到最近我才知道此事。
9．数词：He was among the first to arrive. 他是第一批到的。
10．介词短语：She won’t go home until after the exam. 她要考完试之后再回家。
11．从句：Think of what I said. 想想我说的话。
I’m worried about where he is. 我担心他上哪儿去了。
I have doubts about whether (不用if) he is the best man for the job.我怀疑他是否做这项工作的最好人选。
He has no special fault except that he smokes too much.他除了抽烟太多之外,没有什么特别的毛病。
【注意】除except that, in that等后可接that从句外，介词通常只接连接代词、连接副词及whether引导的从句，也不接if引导的从句。
四、介词的作用：1．作定语：The key to the door is missing. 门上的钥匙丢了。
【注意】介词短语作定语总是放在它所修饰的名词后面。
2．作状语：Marx stayed in Belgium for some time and then went to France.马克思在比利时带了一段时间，然后去了法国。
3．作表语：Japan is to the east of China. 日本在中国的东面。
I always find her at her studies. 我经常发现她在学习。
4．作宾语补足语：Make yourself at home. 别拘谨。
5．作介词宾语：I saw her from across the street. 我从街对面望见了她。
五、常见介词的基本含义：（一）about1.关于，对于a book about ships 关于船舶的书2.在……四周/周围（常用在动词后面），在……一带/附近/身边Gather about the table 围桌而坐Have you a pen about you? 你带着笔吗？3.在……各处，去……各处take the foreign guests about the campus 带外宾参观校园4.（时刻、大小、数量等）近于，大约We left there about six o'clock. 我们大约在6点钟离开那里的。
5.纲要，正准备（常构成be about to）He was about to leave. 他正想离开。
【短语】what about/how about………怎么样？argue about争论ask about询问bring about带来care about在意chat about闲聊complain about报怨go about着手hear about听说hesitate about 对……犹豫不决inquire about打听know about了解look about 环顾四周quarrel about争吵see about+n/doing sth. 安排，着手处理set about doing sth. 着手干某事talk about谈论think about考虑worry about担心be anxious about 为……着急be careless about 对……不关心be cautious about 对……谨慎be concerned about 关心be crazy about为……发狂be curious about 对……好奇be excited about为……激动be mad about为……发疯be nervous about对……紧张be skeptical about 对……怀疑be particular about对……挑剔be worried about担心（二）above1.（表示位置、职位等）在……上面1,000 meters above sea level 海拔1000米2.（表示数量、年龄等）在……以上It weighs above 5 tons. 这东西重5吨以上。
3.（表示品质、行为、能力等）超出……之上The problem is above me. 这个问题我不懂。
【短语】above all 首先above all things 最……above sea level 海拔……above zero 零度以上above oneself 自高自大，兴高采烈above average 超过平均水平的（三）across1.（从表面）横过，穿过，越过，经历a bridge across a river 跨越河流的桥across the century 在整个世纪2.在……的另一边，在……的对面across the sea 在大海的那一边3.与……交叉with a gun across one's shoulder 肩上扛着枪4.与……偶然相遇，偶然发现come across an old friend 偶遇老友【短语】across the street 大街的对面come across 偶遇get sth. across (to sb.)使……被理解，把……讲清楚（四）after1.（时间）在……以后，（位置）在……后面the day after tomorrow后天Shut the door after you.随手关门。
2.（顺序）跟在……后面，（地位或重要性）低于、次于After you! 你先请！He ranked Johnson after Shakespeare. 他给琼森确定的位置上仅仅次于莎士比亚。
3.（一个）接着（一个）day after day 一天又一天4.（与某些动词连用）以……为追求目标，关于What are you after? 你在追求什么？5.仿照，依照，与……相称/相符a play after Shakespeare模仿莎士比亚的剧本【短语】run after sb. 追踪某人，追逐某人after all 毕竟，别忘了look after 照顾be after 寻找one after another 一个接一个one after the other 逐个year after year 年复一年go after 最求，谋求；追赶take after 像（五）against1.逆，（反）对，违反walk against the wind 逆风行走work against 对不利2.倚在，紧靠着lean against the wall 倚在墙上3.以……为背景，以……为衬托，与……对照a design of flowers against a dark wall 深色墙上的花卉图案4.以……为抵御/抵抗的对象a drug against cancer 抗癌药【短语】against one's will 违背某人的意愿be against 反对go against 违反，违背fight against 与……作斗争（六）along1.沿着，循着go for a walk along the road沿路散步2.在……的过程中Somewhere along the journey I lost my hat. 在旅途中的某处我把帽子丢了。