after,before,since用法区别
英语介词知识总结归纳
英语介词知识总结归纳英语介词知识总结归纳篇一一、表示时间的介词时间介词有in , on，at，after，since，during,by,before,after,until等，前三个介词用法有个口诀：at午夜、点与分，上午、下午、晚用in。
年、月、年月、季节、周，之前加上介词in。
将来时态多久后，这些情形亦用in。
日子、日期、年月日，星期之前要用on。
其余几组常见的时间介词辨析如下辨析如下：1、时间介词in与after的用法辨析介词in +一段时间用于一般将来时。
如：We’ll go to school in two weeks.介词after +一段时间用于一般过去时。
如：My mother came home after half an hour.介词after +时间点常用于一般将来时。
如：We’ll go out for a walk after supper.2、时间介词for与since的用法辨析介词for表示一段时间如：I have been living here for 10 years.介词since表示从过去某一时间以来如：I have been living here since 2000.3、时间介词before与by的用法辨析介词before表示“在…之前”如：He won’t e back before five .介词by表示“到…时为止，不迟于…”如：The work must be finished by Friday.4、时间介词during与for的用法辨析当所指的时间起止分明时用介词during如：He swims every day during the summer.如果一段时间不明确则用介词for如：I haven’t seen her for years.5、时间介词till与until用法的异同till和until用在肯定句中，均可表示“直到…为止”，如：I will wait till（until）seven o#39;clock．till和until用在否定句中，均可表示“在…以前”或“直到…才”。
时间状语从句Before-After-Until-Since.doc
时间状语从句Before/After/Until/Since1、时间状语从句（二）由before和after引导的时间状语从句的区别用法▲before引导的从句不再用否定式的谓语，并且当before 引导的从句位于主句之后，有时译成“就，才”。
还要注意主句和从句之间的时间关系。
当主句用将来时，从句总是用现在时；如果before引导的从句谓语用的是过去时，则主句动词多用过去完成时，这样以便体现动作发生的先后。
如：It will be four days before they come back. （主将从现，一一对应）他们要过四天才能回来。
Einstein almost knocked me down before he saw me. （几乎同时发生）爱因斯坦几乎把我撞倒才看到我。
My father had left for Canada just before the letter arrived. （主过完从过）我父亲恰好在信到之前去加拿大了。
They hadnotbeen married four months before they were divorced.他们结婚还不到四个月就离婚了。
▲after表示主句动作发生在从句动作之后。
主句和从句的动作的时间关系正好与before引导的从句相反。
如：After you think it over, please let me know what you decide.你仔细考虑过以后，告诉我你是怎样决定的。
After we had finished the work, we went home.完成工作之后，我们回家了。
（从句用过去完成时，主句用一般过去时）（三）till或until引导的时间状语从句的区别till和until 一般情况下两者可以互换，但是在强调句型中多用until。
但要注意的是：①如果主句中的谓语动词是瞬时动词时，必须用否定形式；②如果主句中的谓语动词是延续性动词时，用肯定或否定形式都可以，但表达的意思不同。
中考英语提高班——时间状语从句 讲义
时间状语从句在复合句中，由时间连接词引导的状语从句叫做时间状语从句。
时间状语从句通常由when, while, as，after, before, since, until等词引导。
一、时间状语从句种类1、引导的从句表示主从句的动作同时发生，或从句的动作在主句之前。
when引导的从句的谓语动词可以是延续性的动词，又可以是瞬时动词。
例如：When she came in, I stopped eating.她进来时，我停止吃饭。
(瞬时动词)When I lived in the countryside, I used to carry some waterfor him.当我住在农村时，我常常为他担水。
(延续性的动词)We were about to leave when he came in.我们就要离开，就在那时他进来了。
2、While引导的从句的谓语动作必须是延续性的，并强调主句和从句的动作同时发生(或者相对应)。
并且while有时还可以表示对比。
例如： While my wife was reading the newspaper, I was watching TV. (was reading是延续性的动词，was reading和was watching同时发生)I like playing football while you like playing bas-ketball.我喜欢踢足球，而你喜欢打篮球。
(对比)3、As表示“一边……一边”，as引导的动作是延续性的动作，一般用于主句和从句动作同时发生;as也可以强调“一先一后。
例如：We always sing as we walk.我们总是边走边唱。
(as表示“一边……一边”)As we was going out, it began to snow.当我们出门时，开始下雪了。
(as强调句中两个动作紧接着先后发生，而不强调开始下雪的特定时间)4、由before和after引导的时间状语从句，表示两个动作一前一后发生。
介 词 的 种 类 及 用 法(二)：表示时间的介词(in、within;before、after;from、since)
介词的种类及用法（二）一，表示时间的介词（in、with；before、after；from、since）1. in、with1). in + 一段时间……后；（此用法多用于一般将来时和过去时）in an hour一小时以后；in five days五天后；in twenty minutes 二十分钟后①.It would strike twelve in twenty minutes' time.再过20分钟，大钟将敲响12下。
②.We will reach the port in three days.我们将在三天后抵达港口。
2).within 在……之内within three days 三天内☞He finished a thick novel within three days.他在三天内就看完了一本厚厚的小说。
●●●辨析：within 和inwithin 强调“在……时间之内”，没有时态的限制in 指从现在起到以后一段时间，只用于一般将来时2. before、after1). before在…以前；☞I am going to finish my homework before Sunday night.我打算在周日晚上之前把作业做完。
2). after在…之后after class 下课后；after school 放学后；after lunch 午饭后☞After school, she plays volleyball with her students.放学后，她与她的学生们一起打排球。
3. from、since1). from 从……起；from…to…从…到；（也表示空间的概念或数字的范围）☞From Monday to Friday are the weekdays.从星期一到星期五是工作日。
2). since 自从……以来（从过去某一时间一直到现在仍在持续）since+ 点时间;①.haven't seen Tom since last year.我从去年就没有见过汤姆。
英语时间状语从句的用法及有关说明
英语时间状语从句的用法及有关说明一、普通类从属连词引导时间状语从句的普通类从属连词有when（当……时），while（在……期间），as（当……，一边……一边……），before（在……之前），after（在……之后），since（从……以来），till/until （直到），whenever（无论何时），as soon as（一……就）等。
如：When I went into the classroom, he was reading. 当我走进教室时，他正在看书。
He read a newspaper as he went along. 他边走边看报纸。
We must strike while the iron is hot. 我们必须趁热打铁。
I will tell you after they leave. 于他们走后我再告诉你。
I told him to come back whenever he wants to.我告诉他什么时候想回来就回来。
I waited till/until she was back. 我一直等到她回来。
Once time is gone, you will never get it back. 时间一旦失去就再也得不到了Things were different when I was a child. 我小时候情况与现在不同。
We must strike while the iron is hot. 我们要趁热打铁。
It’s a long time since I met you last.从上次见到你，已有很长时间了。
He waited until she was about to leave. 他等着一直到她准备离开。
注意：在时间状语从句中，不能用一般将来时、过去将来时态或将来完成时，而要用相应的一般现在时态、一般过去时或现在完成时来代替。
如：I’ll telephone you as soon as I get there.我一到达那里就打电话给你。
before的用法归纳
before的用法是很多的人都比较想要了解的，在众人的心中before的用法是比较难的，我们都非常想要去了解before的用法，但是又谈何容易呢?为了让大家更加快速的了解before的用法，下面我们就和教师一起去看看吧，希望对大家有所帮助。
prep.在……之前;先于，优于;当着……的面;与其……conj.在……之前;在……以前;比……早些;与其……adv.先前，从前;在前，在前方before一词含义广泛，是高考考查的热点词汇之一，但部分考生对该词的用法模糊不清。
为了帮助大家掌握，现就对before的用法归纳如下：一、before用作连词1. before用作连词时，意思是“在……之前;还没来得及…… 就”。
强调主句或从句谓语动词表示的动作发生得过早或过快｡例如：Before she could move, she heard a great noise, which grew to a terrible roar. 她还没来得及动弹，就听见有很响的声音，接着就成了可怕的隆隆轰鸣声。
Before I could say a word, she had stormed out of the room. 不等我说一句话，她就冲出了房间。
Don’t count your chickens before they are hatched. 不要高兴得过早。
I must finish my homework before I watch TV.我必须做完作业才能看电视。
It still took seven years before they finally got married. 过了七年他们才最终得以成婚。
It will be only a few minutes before she comes back. 她过几分钟就会回来。
He announced the ending of the meeting before I could get in a word. 没容得我插上一句话,他就宣布散会了｡Someone called me up in the middle of the night, but they hung up before I could answer the phone.有人半夜给我打电话,但我还未来得及接他就把电话挂断了｡They had talked only a few minutes before they found they were quite different in opinion.他们才谈了几分钟就发现他们的意见很不一致｡注意：before从句若是一个将来的动作，则用一般现在时代替一般将来时，如上句中的comes。
after,before,since用法区别
after，before，since用法区别1.after的用法小结1. 用作介词，与一段时间连用表示“在…之后”时，注意它与in的区别：after表示以过去时间为起点的一段时间以后，且通常与过去时态连用；而in则表示以现在为起点的一段时间以后：He came backafter two days. 他两天后就回来了。
He will come back in twodays. 他过两天就回来。
但after 若是与一点时间连用，则可与过去时态也可与将来时态连用：H e came back after 4 o’clock. 他是四点钟以后回来的。
He will come back after next month. 他将在下个月以后回来。
2. 用作连词引导时间状语从句时注意：若主句用将来时态(或含有将来意味)，则时间状语从句要用一般现在时态(表将来意义)，而不能直接使用将来时态：他回来后我就走。
正：I’ll leave after he comes back.误：I’ll leave after he will come back.3. 用作副词，表示“后来”、“ (一段时间)以后”，通常放在表示时间的副词之后：soon after 不久以后two days after 两天后4. 用于习语after all 终究，毕竟：I was right after all. 毕竟我是对的。
After all, he’s only six years old. 毕竟，他才六岁。
2.Before的用法小结高三课本第十五单元，INTER GATING SKILLS 和WORKBOOK READING部分有如下的句子：⒈The shop was successful，but it was about sixty years before people started to buy jeans for fashion as well as for work.⒉However，it probably will not be long before the other mountainous areas of China such as Sichuan，Xinjiang and Yunnan are developed，and as more facilities become available，prices will almost certainly fall.其中涉及到before的用法，下面就其用法进行总结。
时间状语从句的用法
时间状语从句及用法一、普通类从属连词引导时间状语从句的普通类从属连词有when（当……时），while （在……期间），as（当……，一边……一边……），before（在……之 前），after（在……之后），since（从……以来），till/until（直到），whenever （无论何时），as soon as（一……就）等。
如：When I went into the classroom, he was reading. 当我走进教室时，他正在看书。
He read a newspaper as he went along. 他边走边看报纸。
We must strike while the iron is hot. 我们必须趁热打铁。
I will tell you after they leave. 于他们走后我再告诉你。
I told him to come back whenever he wants to. 我告诉他什么时候想回来就回来。
I waited till/until she was back. 我一直等到她回来。
Once time is gone, you will never get it back. 时间一旦失去就再也得不到了注意：在时间状语从句中，不能用一般将来时、过去将来时态或将来完成时，而要用相应的一般现在时态、一般过去时或现在完成时来代替。
如：I’ll telephone you as soon as I get there. 我一到达那里就打电话给你。
She said she would phone me as soon as she got there. 她说她一到达那里就给我电话。
Don’t get off the bus until it has stopped. 等车停稳后才下车。
二、含 time的短语可引导时间状语从句的time短语有every time, each time, (the) next time, (the) last time, by the time, the first time, any time等。
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after，before，since用法区别1.after的用法小结1. 用作介词，与一段时间连用表示“在…之后”时，注意它与in的区别：after表示以过去时间为起点的一段时间以后，且通常与过去时态连用；而in则表示以现在为起点的一段时间以后：He came backafter two days. 他两天后就回来了。
He will come back in twodays. 他过两天就回来。
但after 若是与一点时间连用，则可与过去时态也可与将来时态连用：H e came back after 4 o’clock. 他是四点钟以后回来的。
He will come back after next month. 他将在下个月以后回来。
2. 用作连词引导时间状语从句时注意：若主句用将来时态(或含有将来意味)，则时间状语从句要用一般现在时态(表将来意义)，而不能直接使用将来时态：他回来后我就走。
正：I’ll leave after he comes back.误：I’ll leave after he will come back.3. 用作副词，表示“后来”、“ (一段时间)以后”，通常放在表示时间的副词之后：soon after 不久以后two days after 两天后4. 用于习语after all 终究，毕竟：I was right after all. 毕竟我是对的。
After all, he’s only six years old. 毕竟，他才六岁。
2.Before的用法小结高三课本第十五单元，INTER GATING SKILLS 和WORKBOOK READING部分有如下的句子：⒈The shop was successful，but it was about sixty years before people started to buy jeans for fashion as well as for work.⒉However，it probably will not be long before the other mountainous areas of China such as Sichuan，Xinjiang and Yunnan are developed，and as more facilities become available，prices will almost certainly fall.其中涉及到before的用法，下面就其用法进行总结。
一、可以用作介词⒈)指时间上早于，在……之前，如：She has lived here since before the war.她从战前就一直在这儿住。
⒉)指位置在前面，如：We knelt down before Grandma‘s grave.我们在奶奶的墓前跪下。
⒊)指顺序或排列在之前，如：Your name comes before mine on the list.名单上你的名字在我之前。
⒋)在某人面前，如：She said it before the witness.他是当着证人的面说的。
二、作为连词其基本含义是“在……之前”，又可以根据不同语境灵活翻译成“才”、“还没来得及就……”、“趁……”、“就”等。
具体用法如下：⒈)与情态动词can/could连用这时候从句虽为肯定形式，根据汉语表达习惯译成“还没来得及就”，如：Before I could get in a word，he had measured me.我还没来得及插话他就为我量好了尺寸。
Before she could move，she heard a loud noise，which grew to a terribl eroar.她还没来得及迈步，就听见一声巨响，接着就是可怕的隆隆轰鸣。
⒉)用于肯定句中强调主句所表达的时间，距离长，或花费的精力大，译成“才” We had sailed four days and four nights before we saw lands.我们航行了四天四夜才看到陆地。
We waited a long time before the train arrived.我们等了很长时间火车才到。
⒊)用于否定句中，强调主句所表达的时间，距离短，或花费的精力小，译成“不到……就”如：We hadn‘t run a mile before he fe lt tired.我们跑了还不到一英里他就累了。
⒋)主句含有hardly，scarcely等半否定副词时可以译为“刚……就”这时候主句应用过去完成时态，从句用过去时，还可以用when替代before如： We had scarcely reached the school before/when the bell rang.我们刚到学校铃声就响了。
⒌)有时还有“宁愿”的意思I‘d shoot myself before I apologiz ed to him.我宁死也不向他道歉。
⒍)用于It+be/take+时间段+before句型在这一句型中又可以根据主从句的时态分成两种情况。
若主句是一般时将来时态，从句是一般现在时.若主句是肯定句意思是“要过多长时间才”；若主句是否定形式翻译成“用不了多久就”。
It will be two weeks before everything returns to normal.两周之后一切才能恢复正常。
It will be many years before the situation improves.这种状况或许要过许多年才能得以改善。
It won‘t be long before we meet again.用不了多久我们就会再见面的。
这时若主句是一般过去时从句也是一般过去时。
若主句是肯定句翻译成“多长时间之后才”，若主句是否定形式翻译成“没过多久就”。
如：It was some time before I realized the truth.过了很长一段时间我才了解到真相。
It wa sn‘t long before she became a brave solider.没过多久她就成了一名勇敢的战士。
After that it still took seven years before they got married.他们又过了七年才结婚。
注意：当主句的谓语动词为延续性动词时，before与until有时可以互换。
It was an hour before/until the police arrived.■巩固练习⒈(2004天津)It was evening ________ we reached the little town of Winchester. Athat B.until C.since D.before2.(2004全国)Several weeks had gone by ________ realized the painting was missing.A.asB.beforeC.sinceD.when3.(2005广东)The America Civil War lasted four years ______ the North won in the end.A.afterB.beforeC.whenD.then4.(2005山东)It was some time _______ we realized the truth.A.whenB.untilC.sinceD.before5.(2006四川)-Why didn‘t you tell him about the meeting？-He rushed out of the classroom _______ I could say a word.A.beforeB.untilC.whenD.after6.(2006福建)-How long do you think it will be __ china sends a manned spaceship to the moon？-Perhaps two or three years.Awhen B.until C.that D.before参考答案：DBBDAD3.Since用法一．时态、现在完成进行时态或过去完成时态连用。
例如：1、He left the village in 1982 and I haven’t seen him since then.1982年他离开这个村子，从那以后我再没见过他。
2、She’s been working in a bank since leaving school.她中学毕业后就一直在一家银行工作。
3.He had spoken to her only once since the party. 自从那次聚会以来，他只跟她说过一次话。
二．Since作为副词，表示从过去以来、以后或到现在的情形或状态，常与现在完成时态连用。
例如：1．He left home two weeks ago and we haven’t heard from him since. 他两周前离开了家，到现在我们一直没有他的消息。
2．He came to Zhenjiang 6 years ago and has lived here (ever) since.他6年前来到镇江，从此便住在这里。
三．since引导原因状语从句作为连词，since可引导原因状语从句，表示因为；既然；鉴于：例如：1．He didn’t come since he was busy.他因为忙，所以没有来。
2．Since this method doesn’t work,let’s try anoter.既然这种方法不行，我们就试用另一种吧。
四．Since在特殊句型中的应用句型I：“It is（has been）+时间+since+持续性动词的过去时”，表示“自从……以来到现在已有多久。
”例如：It has been quite some time since I was last in London.我上次离开伦敦至今颇有一段时间了。
句型II：“It was+时间+since+持续性动词的过去完成时”,表示“从……到过去某时间点以来”，例如：It was three years since we had been here.那时我们在这已呆了三年。
六．巩固练习（一）单项选择1．—Do you smoke？—_____ ．It's two years since I smoked．A．Yes，I do B．No，I don't C．Not too much D．Oh，but I wish I didn't2．Since you are busy, you __________ tomorrow.A. don’t need comeB.need not comeC. needn’t comeD.mustn’t come3.---Has he been home?---______,he _________home since he graduated.A. No; hasn't beenB.Yes;has beenC.No; isn’tD.Yes; is4．They _________friends since they met in Shanghai.A.haven’t beenB.have beenC. aren’tD. are5.I_______here since he left the door open,but it seems that he won’t come back today.A. have been waitingB.will have waitedC.was waitingD.waited6.I _________ from him since he has lived here.A. heardB. have heardC. have never heardD.have been hearing7. He came to China _______ 1998.A. fromB. sinceC. atD. in8.-- Excuse me.Did you notice whether the No.18 bus had gone by?--I don't know_ I began to stand here just now.A.asB.whenC.sinceD.while现在完成进行时和现在完成时练习1. —I’m sur e Andrew will win the first prize in the final.— I think so. He ________ for it for months. (2008江苏)A. is preparingB. was preparingC. had been preparingD. has been preparing2. By the time he realizes he _________ into a trap, it’ll be too late for him to do anything about it. (2008山东)A. walksB. walkedC. has walkedD. had walked3. So far this year we _______ a fall in house prices by between 5 and 10 percent. (2008福建)A. sawB. seeC. had seenD. have seen4. Cathy is taking notes of the grammatical rules in class at Sunshine School, where she ______ English for a year. (2007湖南)A. studiesB. studiedC. is studyingD. has been studying5. Danny _________ hard for long to realize his dream and now he is popular. (2007福建)A. worksB. is workingC. has workedD. had workedＢＣＡＢＡＣＤＣDCDDCfar from 和away from的区别far away 用作表语或状语,away可以省去,因此，far away = far ; far away from = far fromfar （away）后不接宾语；far （away）from 后一定要接宾语。