since从句和 before从句

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。

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。

It+be+时间+before/since/when/that句型辨析I since1. 翻译“It is/has been+时间段+since从句”(1)当从句谓语动词为非延续性动词时，表示这段时间从该动作开始时算起，即“自从做……以来已经多久了”。

(2)当从句谓语动词为延续性动词时，表示这段时间从动作结束时算起，即“自从不做……以来已经多久了”。

It is two years since he joined the army.他参军两年了。

(从参军那一刻算起)It is two years since he was a soldier.他退役两年了。

(从他不再是士兵算起)2. 时态主句为现在时（一般或完成），从句都是一般过去时。

主句为过去式（一般性都用was就够了），从句都是过去完成时II before1. 翻译It was/will be+时间段+before...过多长时间将发生某动作或事情；或过了多久发生了某事或动作。

It was three years before he finished the work.他花了三年才完成这项工作.It will be three years before he finishes the work.他得花三年才能完成这项工作. 2.It won't be/take long before...不久就会…It won't be long before he finishes the work.他不久就会完成这项工作.2. 时态主句为过去式（一般性都用was就够了），从句用过去时主句为将来时，从句用现在时（用一般现在时表示将来）III when1. 翻译It is + 时间点+ when…当发生什么的时候是什么时候…It was one o’clock when he came in .2. 时态主句是什么时态，从句就是什么时态3.常考与强调句的区别It was five o'clock when we arrived at the small mountain village.It was at five o'clock that we arrived at the small mountain village.强调句去掉it、be和that，余下的部分仍是一个完整的句子。

1. It is + 一段时间+ since从句在“ Itis +时间段+ si nee从句”句型中，如果since 从句的谓语动词是瞬间性动词，表示肯定意义；如果since从句的谓语动词是延续性动词，则表示否定意义。

例如：1) It is / has been ten years since he left Beijing.译文：自从他离开北京已经十年了。

分析：si nee从句中的left是leave的过去式，是瞬间性动词，表示肯定的意思，left 译为“离开”2) It is / has been ten years since he wasa doctor.他不当医生已经十年了。

分析：since 从句中的系表结构表示一种状态，这种状态是延续性的，表示否定意义，译为“不是，不当”注：时间的计算一律从since从句的动作完成或状态结束时算起。

2. It was / will be + 一段时间+ before从句1）在“ Itwas + 一段时间+ before 从句”句型中，若主句是一般过去式，从句也是一般过去式时：①若主句是肯定句，翻译成过了多长时间之后才”例：It was long before they found their son. 过了很久他们才找到他们的儿子。

②若主句是否定形式，翻译成没过多久就……”例: It was not long before the couple met again. 没过多久这对夫妻就见面了。

2）在“ Itwill be + 一段时间+ before 从句”句型中，若主句是一般将来时，从句也是一般现在时：①若主句是肯定句，翻译成要过多长时间之后才……”例：It will be half a year before I come back. 半年后，我才回来。

②若主句是否定形式，翻译成用不了多久就……”例：It won't be long before we meet again. 我们不久就会见面。

时间状语从句before 和since的用法before 和since的用法1.连词before表示“还未...就...；不到...就...；...才...；趁...还没...”Before they reached the station, the train had gone.他们(还没)到达火车站前，火车已经开走了。

We hadn’t run a mile before he felt tired.我们跑了还不到一英里他就累了。

Please write it down before you forget it.趁你现在没忘把它记下来。

2.before的句型：It will be +时间段+before从句，表示“多久之后才”。

It won't be long +before从句，表示“不久之后将...”It will be half a year before I come back.半年后我才回来。

(一般现在时表将来)It won’t be long before we meet again.不久后我们将再见面。

3.since的句型：It is/has been+时间段+since从句。

若从句的谓语为非延续性动词，表示“自从动作开始以来有多久了”；若从句的谓语为延续性动词，表示“自从动作结束/完成...有多久了”，常译为“自从不...有多久了”。

It is three years since the war broke out.战争爆发以来，有三年了。

It is twenty years since I've seen her. 我已经二十年没见她了。

五、every time, each time, next time, the first time, any time, all the time 的用法这些短语用来引导时间状语从句，表示“每当..；每次...；下次...”等。

after，before，since用法区别的用法小结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：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。

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。

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。

九大状语从句的引导词时间状语从句：when(当…..时候), while(当….时候) ,as(当..时候,一边), after(在….之后), before(在…..之前), since(自从), ever since(自从)till/until（直到）,not….until(直到..才),as soon as(一．．．就),whenever(不管什么时候)，every time(每次)，each time（每次）next time（下次）,the first time(第一次)any time(任何) the moment（一．．．就．．．）by the time（到．．．）, directly（一．．就．．．）, immediately（一．．．就．．）, instantly（一．．．就．．）, as long as（长达）, hardly/scarcely… when….（一．．就．．）once（一．．就．．）no sooner… than….(一．．．就．．)地点状语从句: where, wherever=no matter where（无论哪里）原因状语从句:because（因为）, as（因为）, since（自．．以来）, for（因为），for the reason that（因为）,considering that, due to the fact that, owing to the fact that, in that（因为）, seeing that（因为），considering that/since （既然）等条件状语从句: if（如果）, unless（除非）, as(so) long as（只要）,in case(万一) on condition that(条件是) supposing(假设),provided that(如果) ，as far as /so far as(就…而言)，even though, even if (即使), providing(that),方式状语从句:as（正如）, just as（就好像，正如）, as if（好像）, as though（好像）让步状语从句: although（尽管）, though（尽管）, even if（即使）, even though（即使）, as, whether…or….（无论．．．．），no matter what /when/how(无论什么，何时，怎样)，now that(既然), despite(尽管),in spite of目的状语从句:that, so that（如此．．．以此于）, in order that（为了）, lest（唯恐）in case(唯恐),结果状语从句: so that, so….that, such…that(如此…….以至于)比较状语从句:as….as（和．．．一样）, not so…..as(not as…..as)（不如．．．）, more…than（多于）less….than, the＋比较级…. ，The＋比较级…..1994-2008高考英语真题状语从句总汇1. — How long has this bookshop been in business? ____________ 1982. ( 94 )A. AfterB. InC. FromD. Since2. Mother was worried because little Alice was ill, especially ______Father was away in France. ( 94 )A. asB. thatC. duringD. if3. If we work with a strong will, we can overcome any difficulty, __________ great it is. ( 95 )A. whatB. howC. howeverD. whatever4. After the war, a new school building was put up _____________ there had once been a theatre. ( 97 )A. thatB. whereC. whichD. when5. — I am going to the post office. _______you’re there, can you get me some stamps? ( 99 )A. AsB. WhileC. BecauseD. If6. You should make it a rule to leave things _____________ you can find them again. ( 99 )A. whenB. whereC. thenD. there7. ____________ you’ve got the chance, you might as well make full use of it. ( 99 )A. Now thatB. AfterC. AlthoughD. As soon as8. We’ll have to finish the job, _____________. ( 99 )A. long it takes howeverB. it takes however longC. long however it takesD. however long it takes9. Someone called me up in the middle of the night, but they hung up ____________ I could answer the phone. ( 00 ) A. as B. since C. until D. before10. The WTO cannot live up to its name _____________ it does not include a country that is home to onefifth of mankind. ( 00 )A. as long asB. whileC. ifD. even though11. The men will have to wait all day ____________ the doctor works faster. ( 01春季)A. ifB. unlessC. whetherD. that12. — Did you remember to give Mary the money you owed her? — Yes, I gave it to her _____ I saw her.( 01春季)A. whileB. the momentC. suddenlyD. once13. Americans eat _____________ vegetables per person today as they did in 1910. (02上海春季)A. more than twiceB. as twice as manyC. twice as many asD. more than twice as many14. — How far apart do they live? _____I know, they live in the same neighbourhood. ( 03上海)A. As long asB. As well asC. As far asD. As often as15. A good storyteller must be able to hold his listeners’ curiosity ______ he reaches the end of the story.A. whenB. unlessC. afterD. until ( 03上海)16. Generally speaking, ____________ according to the directions, the drug has no side effect. ( 03上海)A. when takingB. when takenC. when to takeD. when to be taken17. —Dad, I’ve finished my assignment.—Good, and _____ you play or watch TV, you mustn’t disturb me. ( 03上海)A. wheneverB. whetherC. whateverD. no matter18. — Was his father very strict with him when he was at school?— Yes. He has never praised him _______ he became one of the top students in his grade. (03 北京春季)A. afterB. unlessC. untilD. when19. He made a mistake, but then he corrected the situation ____________ it got worse. (03 北京)A. untilB. whenC. beforeD. as20. _____________ I know the money is safe, I shall not worry about it. (03 北京)A. Even thoughB. UnlessC. WhileD. As long as21. Scientists say it may be five or six years ________ it is possible to test this medicine on human patients.A. sinceB. afterC. beforeD. when ( 04 福建)22. You should try to get a good night’s sleep __________ much work you have to do . ( 04 湖北)A. howeverB. no matterC. althoughD. whatever23. It was evening ________ we reached the little town of Winchester .A. thatB. untilC. sinceD. before24. _____ modeling business is by no means easy to get into, the good model will always be in demand.A. WhileB. SinceC. AsD. If( 04 浙江)25. We were swimming in the lake _______ suddenly the storm started. ( 04 北京春季)A. whenB. whileC. untilD. before26. _______ I can see, there is only one possible way to keep away from the danger. ( 04 北京春季)A. As long asB. As far asC. Just asD. Even if27. We were told that we should follow the main road ________ we reached the central railway station .( 04 辽宁) A. whenever B. until C. while D. wherever28. _____ you call me to say you' re not coming, I'll see you at the theatre. ( 04 四川)A. ThoughB. WhetherC. UntilD. Unless29. You can eat food free in my restaurant ________ you like. ( 04 重庆)A. wheneverB. whereverC. whateverD. however30. _____________ I accept that he is not perfect, I do actually like the person. ( 04 江苏)A. WhileB. SinceC. BeforeD. Unless31. Several weeks had gone by ______I realized the painting, was missing. ( 04 )A. asB. beforeC. sinceD. when32. Jasmine was holidaying with her family in a wildlife park _____ she was bitten on the leg by al lion.( 04 上海) A. when B. while C. since D. once33. ________, I have to put it away and focus my attention on study this week. ( 04上海春季)A. However the story is amusing B No matter amusing the story isC. However amusing the story isD. No matter how the story is amusing34. It is almost five years we saw each other last time.A. beforeB. sinceC. afterD. when35. What a table ! I’ve never seen such a thing before .It is it is long. ( 05 湖北)A. half not as wide asB. wide not as half asC. not half as wide asD. as wide as not half36. Simon thought his computer was broken his little brother pointed out that he had forgotten to turn it on. ( 05 北京春季) A. until B. unless C. after D. because37. I’d like to arrive 20 minutes early _______ I can have time for a cup of tea. ( 05 北京)A. as soon asB. as a resultC. in caseD. so that38. It wasn’t until nearly a month later I received the manager’s reply. ( 05河南、河北)A. sinceB. whenC. asD. that39. Unlike watching TV, reading is a highly active process (过程)________ it requires attention as well asmemory and imagination. （05 江苏）A. untilB. butC. unlessD. for40. The old tower must be saved, _____________ the cost. ( 05 浙江)A. howeverB. whateverC. whicheverD. wherever41. You must keep on working in the evening ______ you are sure you can finish the task in time. ( 05 安徽)A. asB. ifC. whenD. unless42. That was really a splendid evening. It' s years _______ I enjoyed myself so much. ( 05 安徽)A. whenB. thatC. beforeD. since43. John is the tallest boy in the class, ___________ according to himself. ( 05 安徽)A. five foot eight as tall asB. as tall as five foot eightC. as five foot eight tall asD. as tall five foot eight as44. —Did Jack come back early last night?—Yes. I t was not yet eight o’clock he arrived home. ( 05 福建)A. beforeB. whenC. thatD. until45. Allow children the space to voice their opinions, __________ they are different from your own. ( 05 湖南) A. until B. even if C. unless D. as though46. The more I think about him, the more reasons I find for loving him ___ I did. ( 05 湖南)A. as much asB. as long asC. as soon asD. as far as47. you’ve tried it. you can’t imagine how pleasant it is. （06北京）A. UnlessB. BecauseC. AlthoughD. When48. --- How long do you think it will be _________ China sends a manned spaceship to the moon?--- Perhaps two or three years. （06福建）A. whenB. untilC. thatD. before49. Jenny was very sad over the loss of the photos she had shot at Canada, this was a memory she especially treasured. （06广东）A. asB. ifC. whenD. where50. "You can't have this football back you promise not to kick it at my cat again," the old man said firmly. （06广东） A. because B. since C. when D. until51. I had just stepped out of the bathroom and was busily drying myself with a towel ____ I heard the steps. （06湖南） A. while B. when C. since D. after52. _________ environmental damage is done, it takes many years for the ecosystem (生态系统) to recover. （06江苏） A. Even if B. If only C. While D. Once53. He was about halfway through his meal a familiar voice came to his ears. （06辽宁）A. whyB. whereC. whenD. while54. he has limited technical knowledge, the old worker has a lot of experience. （06全国I ）A. SinceB. UnlessC. AsD. Although55. We’re just trying to teach a point ____ both sides will sit down together and talk. （06 山东）A. whereB. thatC. whenD. which56. How can you expect to learn anything ____ you never listen? （06山东）A. in caseB. even ifC. unlessD. when57. His plan was such a good one _________we all agreed to accept it. （06 陕西）A. soB. andC. thatD. as58. This is a very interesting book. I’ll buy it, __________. （06 陕西）A. how much may it costB. no matter how it may costC. however much it may costD. how may it cost59. My parents were quarrelling about me ____ I could not quite tell why. （06上海）A. sinceB. thoughC. ifD. until60. --- Mom, what did your doctor say? --- He advised me to live the air is fresher. （06四川）A. in whereB. in whichC. the place whereD. where61. --- Why didn’t you tell him about the meeting?--- He rushed out of the room I could say a word. （06四川）A. beforeB. untilC. whenD. after62. The cost of living in Glasgow is among the lowest in Britain, the quality of life is probably one of thehighest. （06天津） A. since B. when C. as D. while63. If you are traveling the customs are really foreign to your own, please do as the Romans do. （06天津） A. in which B. what C. when D. where64. In time of serious accidents，_________ we know some basic things about first aid, we can save lives.（06重庆） A. whether B. until C. if D. unless65. ____ most of the earth’s surface is covered by water, fresh water is very rare and precious. （06上海春季）A. AsB. OnceC. IfD. Although66 .He was told that it would be at least three more months he could recover and return work. 2007江西A. whenB. beforeC. sinceD. that67. The field research will take Joan and Paul about five months; it will be a long time _____ we meet themagain.2007安徽 A. after B. before C. since D. when68 In my opinion, life in the twenty-first century is much easier than ________.2007安徽A. that used to beB. it is used toC. it was used toD. it used to be69. Most birds find it safe to sleep in the trees, but ________ they have eggs or young chicks, they don’t use a nest.2007湖南 A. why B. how C. unless D. where70. Pop music is such an important part of society ______ it has even influenced our language. 2007上海A. asB. thatC. whichD. where71. Many of them turned a deaf ear to his advice, _______ they knew it to be valuable 2007浙江.A. as ifB. now thatC. even thoughD. so that72. My parents live in a small village. They always keep candles in the house _____ there is a power out.A. ifB. unlessC. in caseD. so that 2007重庆73. I won’t call you, ________ something unexpected happens. 2007 海南A. unlessB. whetherC. becauseD. while74．________I really don’t like art, I find his work impressive. 2007山东A．As B．Since C．If D．While75. Leave your key with a neighbor ___ you lock yourself out one day2007北京A. ever sinceB. even ifC. soon afterD. in case76. We had to wait half an hour ______ we had already booked a table (2007辽宁.)A. sinceB. althoughC. untilD. before77. Small sailboats can easily turn over in the water ______ they are not managed carefully.A. thoughB. beforeC. untilD. if 2007上海78. Having checked the doors were closed , and _________ all the lights were off, the boy opened the door to hisbedroom. 2007湖南A. whyB. thatC. whenD. where79.---Where’s that report?---I brought it to you ____you were in Mr. Black’s office yesterday. 2007北京A. ifB. whenC. becauseD. before80___ he had not hurt his leg, John would have won the race. 2007 国2A. IfB. SinceC. ThoughD. When81. All people, they are old or young, rich or poor, have been trying their best to help those in need sincethe disaster. （2008重庆）A. even ifB. whetherC. no matterD. however82. You'd better not leave the medicine ______ kids can get at it. （2008山东）A. even ifB. whichC. whereD. so that83. I used to love that film ______ I was a child, but I don't feel it that way any more. (2008辽宁卷)A. onceB. whenC. sinceD. although84. Later in this chapter cases will be introduced to readers __ consumer complaints have resulted in changes inthe law. （2008江西卷） A. where B. when C. who D. which85. -----Have you got any particular plans for the coming holiday?----- Yes, _______, I’m going to visit some homes for the old in the city. （2008安徽卷）A. If everB. If busyC. If anythingD. If possible。