before和until

浅析before和until

在日常的英语教学及考试中，同学们在遇到before和until时，往往会将二者搞错。其实，只要我们能把握住两者在使用时本身的含义及主句动词是终止性的还是延续性的，是肯定式还是否定式两大特点，就能很容易地解决这类问题。现详细阐明如下：

两者可互换使用，但含义略有不同。

一。Before表示“在…之前”，而until表示“直到…才…”，主句肯定表示主句动作的终止时间，主句否定强调动作的起始时间。

1,主句为否定时，谓语动词为终止性动词。常见的动词有open, start, leave, go, arrive, finish, begin, stop, etc. For example:

1), The noise of the street didn’t stop before/until it was midnight.

2), The children won’t come back until/before it is dark.

3), I didn’t leave the lonely boy before/until his mother came home.

2,主句为肯定式，谓语为延续性动词。这类动词有：stand, live, stay, talk, be, wait, etc.

For example:

1). He lived with his parents until/before he graduated from school.

2). I will wait before/until he comes to my help.

3). I shall stay here until/before you come back.

二。下列情况下宜用before不用until.

1。主句为肯定式，谓语为终止性动词时只用before. For example:

1). He fell asleep before I could take off his clothes.

2). We arrived there before it started to rain.

3). The holiday came to an end before I knew it.

4). He almost knocked me down before he saw me.

2。主句谓语动词强调动作的迟缓性，只用before,这时常伴有时间段状语或时间段暗示。For example: It was quite a long time before he found the elephant.过了很长时间，他才找到大象。

We had walked a long way before we found some water.走了很长的路我们才找到水。

We had sailed for two days before we saw the land.航行了两天我们才发现陆地。

It was midnight before my brother came home.我哥哥直到半夜才回来。

3。如果强调从句谓语动作未发生就发生主句谓语动作，只用before,这时常译为“未及（不等）……就……”For example:

1)We can leave early in the morning before it gets too hot.趁天还不太热，我们上午早点离开。

2)I must write it down before I forget it.趁我还未忘，我必须把它记下来。

4。表示“与其说……倒不如……”,“与其……毋宁……”的意思时只用before.

I would give up my job before I agree to be dismissed. 我与其被解雇还不如先辞职。

He will die of hunger before he steals.他宁愿饿死也不愿意去偷。

5．在某些特定句型中用before。

It was (not) long before…（不久）过了很长时间才…

It will (not) be long before…（不到）要过很长时间才会… For example:

It will probably not be long before they understand each other. 他们大概过不久就会互相了解。It was not long before the whole country rose up. 不久全国人民奋起反抗。

三.下列情况一般使用until

1。主句是持续性谓语动词时，肯定,否定都可以，但意义完全不同，肯定表示动作终止，而否定表示动作开始。For example:

1).We discussed the problem until/before he came back. 我们一直讨论到他回来。

2).We didn’t discuss the problem until he came back. 我们一直等他回来才讨论问题。2．Not…until…句型尽管在某些情况下可与before互换使用，但在强调句中一般仍用until; 1). It was not until he told me that I knew it.直到他告诉我我才知道这件事。

2).It was not until he finished his homework that he went home.直到完成作业他才回家。

3放于句首时用until. For example:

Until he finished his homework ，he didn’t go home. 直到完成作业他才回家。

应注意：在使用not until时，若not until放于句首，句子应部分倒装。

For example:Not until he finished his homework，did he go home. 直到完成作业他才回家。

before与ago、when,while,as区别

一、before与ago的区别 1.ago表示“从现在起的若干时间以前”，意思是“距今……以前”，需和过去时或过去进行时连用。before泛指“从过去起的若干时间以前”，意思是“距过去某时……以前”“与其……（毋宁）”，常和完成时连用，尤其在间接引语中，如：I visited him three days ago, but he had gone to Shanghai a week before．我三天前去访问他，但他已与那时的一周前到上海去了。 His parents died ten years ago．他父母十年前都去世了。 He said that his parents had died ten years before．他说他父母亲十年前都去世了。 I have never been there before．我以前从来没有去过那里。 2.如果不具体表明多少时间以前，只用before不用ago，意为“从前、以前”。before仍以副词的形式置于被修饰语后，常与完成时候过去时连用。如： Have you seen this film before? He asked me whether I had been to the Great Wall before． 3.表示在某一点时间或事件以前时，只用before不用ago，这种用法是将before当作介词或连词使用。ago不具有这一功能。如： They will come back before six o’clock． It is hoped that this will be finished before the year 1995．希望这件工作将在1995年以前完成。 另外，before在句中的含义较多。不少句子中，before虽然引导的也是一个时间状语，但是译成汉语时却不必译为“在……以前”。 a.如果before引导的从句动作发生得晚或慢，可译成“……才”。这是主句主语或是名词、代词，或用it作形式主语． He had almost knocked me down before he saw me．他几乎把我撞倒才看见我。 It will be hours before he arrives．要过几个钟头他才回到达。 You must sow before you can reap．有播种才能有收成。 b.如果强调从句动作发生之前，主句动作已发生，可译成“未……就”或“还没有……就”。

keep 的用法

Keep的用法： keep vt., vi. kept, keeping 保留；保守 I keep old letters.我保存旧信。 I'll keep the original copy of your report on file. 我会把你报告的原件归档的。 It's an interesting suggestion and we'll keep it on ice." 这是一项有趣的建议,我们将留待以后考虑采用。" 保持；继续 We will keep on trying and, if we get anything done, will notify you. 我们将继续努力，有结果将通知你。 Leaders shouldn't keep themselves aloof from the masses. 领导人决不应该脱离群众。 Keep calm!安静! You shouldn't keep chopping and changing like this; you'd better make up your mind right now! "你不能再这样变化无常了,最好现在就拿定主意!" 遵守 He keeps to his promise.他守约。 "Everyone should keep discipline, and you, officers are no exception." "每个人都应该遵守纪律,你们军官也不例外。" 保卫；保护 Keep the baby warm.别把婴儿冻着。（常与from连用）防止；抑制 Keep one's temper。抑制住不发脾气。 Keep a curb on your anger.请抑制住怒气。 扣留；留下 Please keep me a place in the queue.请在队里给我留个位置。 赡养；饲养 to keep a dog养狗 Farmers usually keep chickens in their backyard. 农民们通常在自己的后院养鸡。 经营；经销；管理 to keep a shop开商店 to keep house治家 （常与from连用）远离；不接触 Keep away from the scene of the accident.勿靠近事故现场。 Their dog looked dangerous, we decided to keep our distance from it. 他们家那条狗样子很凶恶,因此我们决定离它远一点。 But the stone walls keep the farmer's cows from joining his neighbor's cows. 但是石头墙使这家农民的母牛不会加入到邻居的牛群中去。

before详细用法

after用法小议 通常用于过去时、现在时（主将从现）或完成时态的句子中。 1. 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 back after two days. 他两天后就回来了。He will come back in two days. 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：He 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。 eg. 2. I played computer games after I had finished my homework. 做完功课后，我玩电脑游戏。(从句的动作发生在主句的动作前，因此，主句用一般过去式，从句用过去完成时．) Before和after引导的时间状语从句中，由于before和after 本身的词义已经能够表明动作发生的先后，所以主句可以用一般时代替完成时，也可以用完成时。 I knew/had known her long before you knew her.我认识她早在你认识他之前。 After you finish/have finished all your homework,you can watch TV this evening.你完成所有的作业后，今晚可以看电视。

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)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 The plane was hijacked soon after it took off. Two days later he was gone. 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。 before用法小结 请先看2005年广东省的一道高考题： The American Civil War lasted four years _______ the North won in the end. A. after B. before C. when D. then

浅析before和until的区别

浅析before和until的区别 在日常的英语学习中，我们遇到before和until时，往往会将二者搞错。其实，只要我们能把握住两者在使用时本身的含义及主句动词是终止性的还是延续性的，是肯定式还是否定式两大特点，就能很容易地解决这类问题。 一、在下列情况下，两者可互换用，但含义略有不同。before表示“在……之前”的意思，强调时间先后关系；而until表示“直到……才”的意思，主句是肯定句则表示主句动作的终止时间；主句是否定句则强调主句动作的起始时间。 1.主句为否定式终止性谓语动词。常见的动词是open, start, leave, arrive, finish, stop等。例如： (1)The noise of the street didn’t stop until/before it was midnight. (2)The children won’t come back until/before it is dark. (3)I didn’t leave the lovely boy until/before his mother came home. 2.主句为肯定式、延续性谓语词，这类动词用stand, stay, talk, be, wait等。例如： (1)He lived with his parents until/before he graduated from school. (2)I will wait until/before he comes to my help. (3)I shall stay here until/before you come back. 二、下列情况下宜用before不用until.

详解ago与before的语法难点

详解ago与before的语法难点 1. before还是ago? 要说： I came to Manchester two weeks ago.I came to Manchester two weeks ago. 不要说： I came to Manchester before two weeks. Use past time + ago ago用于一般过去时，例如： 10 years ago, a long time ago, a few weeks ago, a couple of days ago Use before + action / event before用于动作或事件前，例如： before you left, before we start, before lunch 2. fall 还是reduce? These two words are the opposites of rise and raise: 它们是rise和raise的反义词： something falls (e.g. the price fell) somebody reduces something (e.g. the company reduced the price) You will probably use fall to describe numbers on a graph

or chart for IELTS Writing Task 1: 在雅思短作文中，你可以用fall来描述图表里的数字。 In 2008, the number of customers fell. (verb, past) 这里的fall是动词，过去时。 There was a sharp fall in Internet usage. (noun) 这里的fall是名词。 Reduce and reduction are probably more useful for Writing Task 2: reduce和reduction在长作文中更有用： We need to reduce the amount of pollution from exhaust fumes. (verb) reduce，动词。 Recycling leads to a reduction in waste. (noun) reduction，名词。 3. because还是because of? Compare these two sentences: 比较下列两个句子： I stayed at home because the weather was bad. I stayed at home because of the bad weather. The important difference is the use of the word was in the first sentence. After because, you need a subject and a verb (e.g. the weather was). After because of, we dont use a verb,

keep的用法

1.keep +形容词 2.keep+sth/sb +形容词 3.keep +doing 一直做某事 4.keep ... from doing ... 阻止做某事。。。 5.keep a pet 饲养一个宠物 6.How long may I keep this book ？ keep指借。 keep的用法小结 keep是高考常考词汇之一，其含义丰富，与其搭配的短语也很多，其主要用法如下： A、用作及物动词 （1）保留、保存、保持、留下 e.g. We'd better keep a seat for him. 我们最好给他留个座位。 He kept all the money in the bank. 他把所有的钱都存入了银行。 （2）履行（诺言）遵守 e.g. One should keep one's promise. 一个人应当遵守自己的诺言。 Everybody must keep the law. 人人都必须守法。 （3）赡养，养活，饲养 e.g. He has a large family to keep. 他有一大家人要养活。 The old man kept many animals like dogs, pigs and cats. 这位老人养了许多动物，像狗、猪、还有猫等。 （4）经营，管理

e.g. He kept a hotel in this city. 在这座城市里，他开了一家旅店。 She is good at keeping house. 她擅长管理家务。 （5）保守（秘密），记（日记、帐） e.g. All of the people keep the Spring Festival in our country. 我国所有的人都庆祝春节。 Some of them keep birthdays. 他们中有些人庆祝生日。 （7）使……处于某种状态（情况） 在这种情况下，keep常跟复合结构（keep＋宾语＋补语）。用作宾语补足语常见的词有现在分词、过去分词、形容词、副词以及介词短语。 e.g. He kept me waiting for half an hour. 他让我等了半个小时。 Keep your mouth shut and your eyes open. 少说话，多观察。 The doctor kept me in for a week. 医生一周没让我出去。 He always keeps his books in good order. 他总是把书放得整整齐齐。 B、用作不及物动词 （1）保持、继续（处于某种状态）（keep为连系动词）

before的详细用法

before的详细用法 Before 在英语中是一个比较常用的虚词，它既可作介词或副词用，也可作从属连词用。在近几年的高考试题中常常出现考查其从属连词用法的题目。其用法如下： 1.表示“在…..之前就…..”。 Mary had finished her homework before her mother returned. 2.表示“过了多久后才…….. ，动作进行到什么程度才……” They walked about 30 miles to the west before they saw a village . 3.表示“来不及；尚未…..就…” He ran off before I could stop him . 4.表示“刚…就…” I had hardly sat down before the bell rang. 5.表示“不知不觉就…..；还没弄清就……” Time passed quickly and three months went by before Aqiao knew it. 6.表示“宁愿…，决不…，与其…，毋宁….”常与will 或would 连用。 I would / will die before I surrender . 7.表示“否则；以免” I will write it down before I forget it . 8.用于句型“it was+时间段+ before …” 表示“过了多久才…” It was three days before he came back. . 9.用于句型“ it was not long +时间段+ before …” 意为“不久就….” It was not long before he sensed the danger of the position . 10. 用于句型“it will be(not )+时间段+ before….”表示“要过多久/ 不久…才…” It will be half a year before you graduate from this school .

ago和before的区别及用法有哪些

ago 只作副词，必须与一段时间连用，表示以现在为起点一段时间之前。before既可以作副词也可以作连词。作副词时，可以单独使用;也可以和一段时间的词连用，表示的是已过去某个时间为起点一段时间之前。 ago 和before的区别 1、意思不同 ago 表示“从现在起若干时间以前”。 before 表示“从过去某时起若干时间以前”。 2、词性不同 ago只能作副词。 例句： She left England three days ago. 她三天前离开了英格兰。 before既可作副词又可作介词和连词。 例句： Please close the window before you leave. 离开前请关好窗户。(连词) 3、后接单词不同 ago常与动词一般过去式连用。 例句： His grandfather died two years ago. 他的外公两年前去世了。 before常与过去完成式连用。

例句： I had finished the work two days before. 两天前我就已经完成了工作。 ago的用法 1、用于一般过去时。 例句： A short while ago, my sister helped me to carry one of my old bookcases up the stairs. 片刻之前，我妹妹帮我把我的一个旧书柜抬上了楼。 2、所指的时间是从现在算起。 例句： It was stolen twenty years ago when Ted was a boy of fifteen. 那辆自行车是在20年前当泰德还是个15岁的小伙子时被偷去的。 before的用法 1、用于过去完成时 例句： A short time before, great trees had covered the countryside for miles around. 在那时不久之前，高大的树木覆盖着方圆数英里的地方。 2、它所指的时间不是从现在算起，而是从过去某一时刻算起，有时可以与previously 换用 例句： Last summer, I finally left the firm that I had joined eighteen years

keep的用法

用作动词(v.) keep about〔around〕1( v.+adv. ) 1. 继续履行职责go on with one's duties keep about〔around〕 She is very ill, but she still keeps about. 她虽然病得很重,但仍然继续工作。 2. 使手边常有have sth always present keep sth ? about〔around〕 I like to keep a few envelopes around in case I need them.我喜欢手边常有几个信封,以应不时之需。 keep about〔around〕2 ( v.+prep. ) keep abreast of( v.+adv.+prep. ) keep after( v.+prep. ) keep aloof( v.+adv. )

keep apart( v.+adv. ) keep at( v.+prep. ) keep away( v.+adv. ) keep away from( v.+adv.+prep. ) keep back( v.+adv. ) keep behind1( v.+adv. ) keep behind2 ( v.+prep. ) keep by1( v.+adv. ) keep by2( v.+prep. ) keep down( v.+adv. ) keep for( v.+prep. ) keep from( v.+prep. ) keep going( v.+adj. ) keep in1( v.+adv. ) keep in2( v.+prep. )

before／ago,since用法

before和ago都能表示在一段时间以前，但是二者的内涵和具体用法有明显的区别： 1. before表示从过去或将来某一时间算起多少时间以前，由于与这一时间状语连用的行为先发生在过去或将来某一时刻之前，因此往往出现在过去完成时态或将来完成时态中。例如： ①I called him up last night，but his mother told me he had left for Wuhan two days before. ②She said that she had married him five years before. 2.如果不具体表明多少时间以前，before意为"从前；以前"，表示从现在开始追溯到过去一段时间，或者主句的谓语动词表示的是经常、反复发生的行为，以副词的形式置于句末，可以用在现在完成时态中。例如： ①I have never been to Beijing before. ②Have you ever seen a tiger before? ③I often go over the lessons that I have learned a few days before. 注意：before前的时间状语如果是特定的，含义不一样。试比较： He said he had arrived here a day before. (一天前) He said he had arrived here the day before. (前一天) 3. ago指的是从现在起到过去时间的某一点的一段时间。这个时间状语常与一般过去时态或过去进行时态连用。例如： ①I graduated from the college twenty years ago. ②I was asked what I was doing a month ago. 4. 表示在某一时间点或事件以前时，只能用before，不用ago。因为这种用法是将before当作介词或连词使用。ago不具有这种功能。例如： ①He will come back before eleven o'clock.

Keep_用法

Keep 用法知多少 keep 是英语中用法灵活的动词之一，用法归纳如下： 一、用作系动词，意为“保持（某种状态）”，其后常接形容词作表语。如： Please keep quiet / silent! 请保持安静！ After the accident, he still kept alive. 这次事故之后，他仍然活着。 二、用作实义动词，可表示： 1. 保管；保存；保留。如： Keep the change. 零钱不用找了。 Please keep these things for me while I am away. 在我离开期间，请你替我保管这些东西。 2. 赡养；饲养。如： Does he earn enough to keep himself and his family? 他的收入够养活他自己和他的家人吗？ I used to keep sheep in my childhood. 我在孩提时常常养羊。 3. 经营。如： Her father kept a grocer's shop for a number of years. 她父亲开了几年杂货店。 4. 坚持；继续。后面如接动词，要用V-ing 形式作宾语。如： If you keep (on) practising your spoken English, you'll soon make great progress. 如果你坚持练习英语口语，你很快就会取得很大的进步。 5. 阻止；阻碍。常用于keep sb/sth from doing sth 结构中，其中介词from 不能省略。如： The heavy rain didn't keep them from watching the football match. 大雨没能阻止他们观看足球赛。 6. 保持。其后常接复合宾语，表示使（某人或某物）保持某种状态或使某一动作继续。 ①keep + sb/sth + 介词。如：

before的用法

before的用法 1．表示“在……之前”。说明两个时间或两个事件之间的先后关系。 1)They had got everything ready before I arrived．在我到达之前他们已经把一切都准备好了。 2)She didn’t understand me before I explained it to her．在我向她解释之前，她不理解我的意思。 3)The train had left before I arrived at the station．在我到达车站之前火车已开走了。2．表示“……才…… ”，强调从句的谓语动词所表达的时间、距离很长或花费的力量比较大。 1)The workers worked long hours for two weeks before everything returned to normal．工人们长时间地工作了两周，一切才恢复正常。 2)The big fire lasted four hours before the firemen brought it under contro1．大火持续了四个小时，消防队员才把它控制住。 3) We waited a long time before the train arrived．我们等了很长时间火车才到。 3．表示“还未来得及……就……”，强调主句谓语动词所表达的时间、距离很短或花费的精力比较小。 1)Before I could figure out what had happened，he forced me into the car．我还不知道发生了什么，他就强行把我推进了汽车。 2)He jumped into the water before I could stop him．我还没有来得及阻止他，他就跳进了水里。 3)Her father died before she was born．她尚未出世父亲就去世了。 4．表示“趁着……”。 1)We can set off early before it gets hot．我们可以趁着天不热早点出发。 2)You’d better write the phrases down before you forget them．趁着你还没有忘记，赶紧把这些词组写下来。 3)Please put them away before they are missing．趁着他们还没有丢，把它们收好吧。5．表示“一……就”、“刚刚……就”。与hardly．scarcely连用o 1)He had hardly gone to bed before(=when)the door bell rang．他刚刚睡下，门铃就响了。 2)She had scarcely got off the train before(=when)her daughter ran towards her．她刚一下车，女儿就跑了过来。 6．表示“不知不觉多少时间已经过去了”。 1)He was so absorbed in his work that four hours had passed before he knew it．他如此专注于工作，不知不觉四个小时就过去了。 2)Time passed quickly and three months went by before he knew it．时间飞快地流逝，他没感觉到三个月已过去了。 7．表示“宁可,宁愿”，相当于rather than。 1)I’d die b efore I apologized to them．我宁死也不向他们道歉。 2)1 would be poor before I got money in this way．我宁愿穷也不愿用这种方式挣钱。8．before常用于句型 “it was +段时间+before……”“过了(多长时间)才…… ”; “it will be……before…… ”“要用(多长时间)才……”; “it wasn’t……before……”“没过(多长时间)就……”; “it won’t be……before……”“用不了(多长时间)就会……”。 1)It was long before he came to help me．过了很久他才来帮我。 2)It wasn’t long before the fire was put out．不久火就给扑灭了。

Until的详细用法总结

Until的详细用法总结 你们知道until用法吗?我们一起来学习学习吧，下面就和大家分享，来欣赏一下吧。 Until的用法 比较until和till 此两个连词意义相同。肯定形式表示的意思是"做某事直至某时"，动词必须是延续性的。否定形式表达的意思是"直至某时才做某事"。动词为延续性或非延续性都可以。正确使用这两个连词的关键之一就在于判断句中的动词该用肯定式还是否定式。 肯定句： I slept until midnight. 我一直睡到半夜时醒了。 Wait till I call you. 等着我叫你。 (在肯定句中可用before代替Lets get in the wheat before the sun sets.) 否定句： She didnt arrive until 6 oclock.

她直到6点才到。 until 用法上的三个难点 一、 1. until用在肯定句,谓语动词通常是延续性动词,如stand, stay, talk, wait等,表示主句动作终止的时间。如: ③I waited until he cam e back.我一直等到他回来。 ④The war lasted until 1945.战争持续到1945年。 如果用在否定句,谓语动词通常是瞬间性动词,如open, start, leave, arrive, finish, stop等,强调主句动作开始的时间。如: ⑤I didnt leave the boy until his mother turned up.直到这孩子的母亲来,我才离开。 ⑥The noise of the street didnt stop until it wa s midnight.街上的噪音直到半夜才停止。 2.连词until引导的从句中谓语动词的时态 1)until后面的从句中不能用一般将来时，应该用一般现在时代替。所谓的“主将从现”。 He will stay here until his mother comes back.

中考英语keep用法归纳

Keep用法归纳 在人教版初中英语教材中，keep是要求学生必须掌握的四会词之一，现将其多见用法归纳小结如下，以利于大家正确地使用该词。 一、用作及物动词 1.意为“保存；保留；保持；保守“。如： Could you keep these letters for me, please?你能替我保存这些信吗？ I“ll keep a seat for you.我给你留个座位。 It can help to keep vegetables, fruit and meat for a long time in hot summer.在炎夏的夏天，它有助于蔬菜、水果和肉类长时间保鲜。 Can you keep a secret?你能保守秘密吗？ 2.意为“照顾；养活“等。如： She kept her sister for a week while her sister was ill.她妹妹有病时，她照看她了一个星期。 I have a family to keep.我得养活一家人。 3.意为“留下；不必还“。如： You can keep the pen if you like it.你要是喜欢就把钢笔留下吧。 Keep the change.不用找零钱了。 4.意为“遵守；维护“。如： Everyone must keep the rules.人人必须遵守规章制度。 The teacher is keeping order in class.老师正在课堂上维持秩序。 5.意为“售；卖“。如： The shop keeps everything you need.那家商店里出售的东西应有尽有。

before用法

1．表示“在……之前”.说明两个时间或两个事件之间的先后关系. 1)They had got everything ready before I arrived． 在我到达之前他们已经把一切都准备好了. 2)She didn’t understand me before I explained it to her． 在我向她解释之前,她不理解我的意思. 3)The train had left before I arrived at the station． 在我到达车站之前火车已开走了. 2．表示“……才……”,强调从句的谓语动词所表达的时间、距离很长或花费的力量比较大. 1)The workers worked long hours for two weeks before everything returned to normal．工人们长时间地工作了两周,一切才恢复正常. 2)The big fire lasted four hours before the firemen brought it under contro1．大火持续了四个小时,消防队员才把它控制住. 3) We waited a long time before the train arrived．我们等了很长时间 火车才到. 3．表示“还未来得及……就……”,强调主句谓语动词所表达的时间、距离很短或花费的精力比较小. 1)Before I could figure out what had happened, he forced me into the car．我还不知道发生了什么,他就强行把我推进了汽车. 2)He jumped into the water before I could stop him． 我还没有来得及阻止他,他就跳进了水里. 3)Her father died before she was born．她尚未出世父亲就去世了. 4．表示“趁着……”. 1)We can set off early before it gets hot． 我们可以趁着天不热早点出发. 2)You’d better write the phrases down before you forget them． 趁着你还没有忘记,赶紧把这些词组写下来. 3)Please put them away before they are missing． 趁着他们还没有丢,把它们收好吧. 5．表示“一……就”、“刚刚……就”.与hardly．scarcely连用 1)He hadhardly gone to bed before(=when)the door bell rang． 他刚刚睡下,门铃就响了. 2）She had scarcely got off the train before(=when)her daughter ran towards her．她刚一下车,女儿就跑了过来. 6．表示“不知不觉多少时间已经过去了”. 1)He was so absorbed in his work that four hours had passed before he

when, if, before, until从句

when if before until引导的从句 由一个主句和一个或多个从句构成的句子叫复合句。主句是复合句的主干部分，从句是修饰主句或主句的某个成分的。从句不能单独成句，但具有主语和谓语，须由关联词引导。根据从句在主句中充当不同的成分，可分为不同的从句，例如，主语从句、宾语从句、表语从句、同位语从句、定语从句、状语从句等。 由when, if, before, until引导的从句 一、when引导的时间状语从句 (1) when引导时间状语从句时，表示“当……的时候” ① when既可以指时间段也可指时间点 Her brother was very fat when he was a child. 她哥哥小时候很胖。 They were talking when the teacher came in. 老师进来的时候，他们正在讲话。 ② when从句中既可用延续性动词又可用非延续性动词 You should keep your room clean and tidy when you live here. 在你住在这里的时候，你应该保持你房间干净、整洁。 When he arrives, he’ll tell us about the match. 他回来的时候就会告诉我们比赛的情况。 ③ when从句动作既可和主句的动作同时发生又可在主句的动作之前或之后发生Mary was doing her homework when her father was reading newspapers. 玛丽的爸爸在看报纸的时候她正在做作业。 I’ll call you when I get to the airport. 我一到机场就给你打电话。 二、if引导的条件状语从句 条件状语从句表示主句动作发生的条件，条件有真实和非真实两种。if引导条件状语从句时，意为“如果，假如”，表示在某种条件下，某事很可能发生。 if除了引导条件状语从句，还可引导宾语从句。 if引导的条件状语从句和宾语从句的区别： （1）if 在句中的含义不同 If 在宾语从句中翻译为“是否”,相当于whether I want to know if he is a teacher. If 在条件状语从句中翻译为“如果” I’ll go to see you if I am free next week.

Before和ago的区别(精华版)

before和ago的区别 before和ago都能表示在一段时间以前，但是二者的内涵和具体用法有明显的区别： 1. before表示从过去或将来某一时间算起多少时间以前，由于与这一时间状语连用的行为先发生在过去或将来某一时刻之前，因此往往出现在过去完成时态或将来完成时态中。例如： ①I called him up last night，but his mother told me he had left for Wuhan two days before. ②She said that she had married him five years before. 2.如果不具体表明多少时间以前，before意为"从前；以前"，表示从现在开始追溯到过去一段时间，或者主句的谓语动词表示的是经常、反复发生的行为，以副词的形式置于句末，可以用在现在完成时态中。例如： ①I have never been to Beijing before. ②Have you ever seen a tiger before?

③I often go over the lessons that I have learned a few days before. 注意：before前的时间状语如果是特定的，含义不一样。试比较： He said he had arrived here a day before. (一天前) He said he had arrived here the day before. (前一天) 3. ago指的是从现在起到过去时间的某一点的一段时间。这个时间状语常与一般过去时态或过去进行时态连用。例如： ①I graduated from the college twenty years ago. ②I was asked what I was doing a month ago. 4. 表示在某一时间点或事件以前时，只能用before，不用ago。因为这种用法是将before当作介词或连词使用。ago不具有这种功能。例如：

keep用法

?keep at 1.坚持做…：继续某项工作或行为 ?keep down 1.压制，镇压：阻止…成长、完成或成功 Keep down prices; keep the revolutionaries down. 控制物价；镇压革命 ?keep off 躲开，避开 ?keep to 1.坚持，信守Keep to the original purpose.遵守原定宗旨 ?keep up 1.保持良好状态Kept up the property保存财产 2.保持；继续We asked her to stop talking, but she kept up. 我们请她别再说话了，但她依旧说下去 3.并行：按相同的水平或步伐继续下去 4.不落后，赶得上：赶上对手、同事或邻居，指在成就或生活方式上 Unsuccessfully tried to keep up with his associates.没能赶上他的同事们 ?you can't keep a good man (或woman) down (非正式)有能力的人是不会被挫折或问题吓倒 ?keep one's feet 站稳，不倒 ?keep goal (主英足)守球门 ?keep going (困难时）努力维持正常生活 ?keep open house 好客 ?keep to oneself 避开与人接触，独处 ?keep something to oneself 守口如瓶 ?keep up with the Joneses 与人攀比 ?keep wicket (板球)守板球门 ?keep someone after (美)（作为对小学生的惩罚）放学后留校