高考英语（牛津译林版）一轮总复习配套课件：语法专题突破 专题二三大从句（共93张）

1、从句可分为定语从句、状语从句和名词性从句，它们是中学阶段的重要语法项目。定语从句是形容词性从句，相当于形容词的用法，其功能是修饰先行词，对其性质、特征进行描述，先行词在定语从句中一般充当主语、宾语、表语、定语或状语等。状语从句是副词性从句，相当于副词的用法，其功能是在复合句中作状语。根据状语从句的含义，状语从句一般可以充当时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。名词性从句的功能相当于名词词组，一般在句子中充当主语、表语、宾语或同位语。三大从句的考查历年都是高考的重点，关联词的选择是高考的主要考点，定语从句中对which的考查，宾语从句中对what和that的考查，让步、时间

2、和条件状语从句的考查是重中之重。 一、三大从句的区别三大从句存在一定的关联性，应抓住关键点，确定是何从句。试比较：It is known to all that the moon travels around the earth.(主语从句)As is known to all, the moon travels around the earth.(定语从句)What is known to all is that the moon travels around the earth.(主语从句与表语从句)The news (that/which) they won the match is t

3、rue.(同位语从句)The news that you told me yesterday is true. (定语从句)This is such a difficult problem as few of us can solve.(定语从句)This is such a difficult problem that few of us can solve it.(结果状语从句)He has found the book (that/which) he lost.(定语从句)He has found the book where he lost it.(地点状语从句)高考体验1(2013陕

4、西卷)_is often the case with children, Amy was better by the time the doctor arrived.AIt BThat CWhat DAs答案D考查非限制性定语从句。句意：对于孩子来说经常会有这样的情况发生，当医生到达时，Amy(比之前)好多了。根据句意并分析句子成分可知，空处引导一个非限制性定语从句，指代后面整个句子，又因为在句首，所以要用as引导该定语从句，as在从句中作主语。2(2013重庆卷)_struck me most in the movie was the fathers deep love for his so

5、n.AThat BIt CWhat DWhich答案C考查主语从句。句意：这部电影最打动我的是父亲对他儿子深深的爱。“_struck me most in the movie”为主语从句，所填词在从句中作主语，表示“什么”，故用what引导。二、三大从句各自的关联词定语从句的引导词有关系代词和关系副词之分；名词性从句连接词分为连词、连接代词和连接副词。状语从句的连词也有意义和结构之分，因此，选择关联词要综合各方面因素来考虑。注意以下几点：(1)what不能引导定语从句。(2)whether/if不能引导定语从句。(3)that不能引导非限制性定语从句。 (4)that既可引导定语从句也可以引导

6、同位语从句，但that在定语从句中可作主语、表语和宾语，而that在同位语从句中不作成分，只起连接作用。(5)which在定语从句中常可以替换that，但在名词性从句中不可以替换。高考体验1(2011陕西卷)_all of them are strong candidates, only one will be chosen for the post. ASince BWhile CIf DAs答案B考查状语从句。句意：虽然他们都是很强的候选人，但是只有一个人能被选来担任这一职务。根据句意应该选B, while 此处意为“虽然” 引导让步状语从句。2(2011上海卷)There is clea

7、r evidence _ the most difficult feeling of all to interpret is bodily pain.Awhat Bif Chow Dthat答案D考查同位语从句。句意：有确凿的证据表明，所有感觉中最难演绎的是身体上的痛苦。分析句子结构可知空格处引导的是evidence的同位语从句，从句结构和意义完整，故用that引导。3(2010新课标卷)As a child, Jack studied in a village school，_is named after his grandfather.Awhich Bwhere Cwhat Dthat答案

8、A考查定语从句。题干中先行词的后面有逗号，故后面的定语从句为非限制性定语从句，而定语从句中is前缺少主语，故只能用关系代词which。三、定语从句中which的考查which既可引导限制性定语从句也可引导非限制性定语从句，在从句中作主语、宾语或表语，高考中的考查重点是which在非限制性定语从句中的应用。which引导非限制性定语从句时，常代指整个主句。We have launched another manmade satellite, which is announced in todays newspaper. (2013天津卷)报纸新闻报道说，我们又发射了一颗人造卫星。高考体验1(20

9、13江苏卷)The president of the World Bank says he has a passion for China，_ he remembers starting as early as his childhood.Awhere Bwhich Cwhat Dwhen答案B考查定语从句。分析句子结构可知，“_he remembers starting as early as his childhood”为定语从句，先行词是passion，且空处在从句中作宾语，因此选which。2(2013安徽卷)Mo Yan was awarded the Nobel Prize for

10、 Literature in 2012，_made one of the Chinese peoples longheld dreams come true.Ait Bthat Cwhat Dwhich答案D考查定语从句。句意：莫言获得了2012年诺贝尔文学奖，这使得中国人民很久以来的一个梦想得以实现。此处为非限制性定语从句，修饰整个主句。it和what不能引导定语从句，可排除；that不能用于引导非限制性定语从句。四、定语从句中where的考查where引导定语从句时，在从句中作状语，主要有以下两种情况：(1)表示具体的地点Stephen Hawking believes that the

11、earth is unlikely to be the only planet where life has developed gradually.(2010福建卷)史蒂芬霍金认为，地球可能不是唯一有生命进化的行星。(2)表示模糊的地点和抽象意义的地点(常见的先行词有race, job, activity, case, situation, point, position, stage, degree等)They have reached the point where they have to separate with each other.他们已经到了必须分手的地步。高考体验1(201

12、3新课标卷)When I arrived, Bryan took me to see the house _I would be staying.Awhat Bwhen Cwhere Dwhich答案C考查定语从句。句意：当我到达时，布莱恩带我去看了我即将居住的房子。分析句子结构可知，此处为定语从句，从句中缺少地点状语，应用关系副词where来引导。2(2013江西卷)He wrote a letter _ he explained what had happened in the accident.Awhat Bwhich Cwhere Dhow答案C考查定语从句。句意：他写了一封信，在信中

13、他解释了在那起事故中发生了什么。分析句子成分可知，空处引导定语从句，a letter是先行词，且关系词在从句中作地点状语，故用where引导。where在这里相当于in which。五、名词性从句中what的考查what引导名词性从句时表示“所有的事物、东西，凡是的事物”，充当从句的主语、宾语、表语或定语。The message you intend to convey through words may be the exact opposite of what others actually understand.(what在从句中作宾语)(2011上海卷)你想用语言所传达的信息可能与他人

14、所理解的恰恰相反。高考体验1(2013新课标卷)Police have found _ appears to be the lost ancient statue.Awhich Bwhere Chow Dwhat答案D考查名词性从句。句意：警察找到的东西似乎是那尊丢失的古代雕像。分析句子成分可知，空处引导宾语从句，且在从句中作主语，故用what。2(2013北京卷)_makes the book so extraordinary is the creative imagination of the writer.AThat BWhat CWho DWhich答案B考查主语从句。句意：让这本书如

15、此非凡的是作者创造性的想象力。所填词引导主语从句，并在从句中作主语，故选B。六、名词性从句中that的考查that引导名词性从句时，没有词义，不作句子的任何成分，只起连接词的作用。Experts believe that people can waste less food by shopping only when it is necessary. (2013北京卷)专家认为可以通过只有需要食物时才购物这一方法减少食物的浪费。高考体验1(2013山东卷)Its good to know _the dogs will be well cared for while were away.Awha

16、t Bwhose Cwhich Dthat答案D考查宾语从句。句意：得知我们离开时狗会得到很好的照顾真高兴。分析句子成分可知，所填词引导宾语从句，而且在从句中不作任何句子成分，故选D。2(2012北京卷)Jerry did not regret giving the comment but felt _he could have expressed it differently.Awhy Bhow Cthat Dwhether答案C 考查宾语从句。句意：Jerry不后悔给出评论，但是觉得自己本来可以用不同的方式来表达。that he could have expressed it differ

17、ently是由that引导的宾语从句，作felt的宾语。that在从句中不作成分。七、名词性从句中whether的考查whether为连词，在从句中不作任何成分，意为“是否”， 表示不肯定，不把握，有疑问等意义。It doesnt matter whether you pay by cash or credit card in this store.(2012山东卷)在这家商店，你是用现金还是信用卡支付都没有关系。高考体验1(2013陕西卷)It remains to be seen _the newly formed committees policy can be put into pra

18、ctice.Athat Bwhich Cwhat Dwhether答案D考查主语从句。句意：这个新形成的委员会的政策能否实施还有待观察。分析句子结构可知，It作形式主语，而真正的主语是后面的从句“_the newly formed committees policy can be put into practice”；再根据句意来判断，此处表示“是否”的意思。故选D。2(2012安徽卷)The limits of a persons intelligence, generally speaking, are fixed at birth, but_he reaches these limits

19、 will depend on his environment.Awhere Bwhether Cthat Dwhy答案B考查主语从句的引导词。句意：一个人的智力极限，通常来说，出生时就已经定型了，但他是否能够达到这些极限则取决于他的生活环境。根据“depend on”可知，主语从句“ _ he reaches these limits”中含有不确定因素，故用whether，选B。 八、让步状语从句让步状语从句的常用连词有 although, though, even if, even though, as(从句需要倒装), while (一般置于句首), no matter 疑问词， 疑问词

20、ever。While I always felt I would pass the exam, I never thought I would get an A(2012湖南卷)尽管我一直觉得自己能通过考试，但是我从未想到会得A。However serious a problem you may have, you should gather your courage to face the challenge.(2010上海卷)不论你的问题有多严重，你都应该鼓起勇气，接受挑战。高考体验1(2013江苏卷)In the global economy, a new drug for cancer

21、, _it is discovered, will create many economic possibilities around the world.Awhatever BwhoeverCwherever Dwhichever答案C考查状语从句。分析句子结构可知，“_it is discovered”为状语从句，空处在从句中作地点状语，因此选wherever“无论在哪里”，引导让步状语从句。2(2013四川卷)He is so busy. He cannot afford enough time with his son _he wants to.Aeven if Bas ifCbeca

22、use Dbefore答案A考查状语从句。句意：他很忙。即使他想陪他的儿子也没有足够的时间。even if引导让步状语从句；as if引导方式状语从句；because引导原因状语从句；before引导时间状语从句。One Friday, we were packing to leave for a weekend away when my daughter heard cries for help.(2011浙江卷)一个星期五，我们正在收拾行李去度周末，这时我的女儿听到求救的呼喊。(2)下列结构表示“一就”：as soon as, immediately, directly, instantl

23、y, the moment, the minute, the instant, no sooner .than ., hardly/scarcely .when .The moment I heard the voice，I knew father was coming.我一听到那个声音就知道父亲来了。He had no sooner finished his speech than the students started cheering.(2011辽宁卷)No sooner had he finished his speech than the students started chee

24、ring.他刚完成演讲学生们就开始欢呼起来。 (3)before表示“还未就；不到就；才；趁；还没来得及就”。The girl had hardly rung the bell before the door was opened suddenly, and her friend rushed out to greet her.(2010福建卷)小女孩还没来得及按门铃，门就突然开了，并且她的朋友冲出来问候她。It will be一段时间before .“多久之后才”。It is一段时间since .“自从多久了”。It will be half a year before I come bac

25、k.还得再过半年我才能回来。 (4) by the timeby the time 表示“到的时候”。当从句是用它引导的时间状语从句时，主句要用完成时。By the time you come back, well have finished the job.当你回来的时候，我们将已完成这项工作。He had planted 10 trees by the time we arrived.我们到的时候，他已经种了10棵树了。高考体验1(2013湖南卷)You must learn to consult your feelings and your reason _you reach any d

26、ecision.Aalthough BbeforeCbecause Dunless答案B考查时间状语从句。句意：作任何决定之前你都要顾及自己的情感和理智。此处用before引导时间状语从句。“顾及自己的情感和理智”与“作任何决定”是一种先后关系，前者在后者之前，因此用before。2(2011四川卷)As is reported, it is 100 years_Qinghua University was founded.Awhen BbeforeCafter Dsince答案D考查状语从句。since conj. “自以来，从以后”，引导时间状语从句。句意：据报道，自清华大学建立以来已有一

27、百年了。It is一段时间since从句表示“自从以来已有多长时间了”。十、条件状语从句条件状语从句的常用连词有if, unless, as/so long as(只要), only if(位于句首主句要倒装), in case, on condition that等。Once they decide which college to go to, students should research the admission procedures.(2010北京卷)学生一旦决定上哪所大学，他们就应该了解一下入学手续。高考体验1(2013江西卷)She says that shell have

28、to close the shop _business improves.Aif Bunless Cafter Dwhen答案B考查状语从句。句意：她说她将不得不关掉商店，除非生意好转。根据句意可知选B项。2(2013重庆卷)_ we have enough evidence, we cant win the case.AOnce BAs long asCUnless DSince答案C考查状语从句。句意：除非有足够的证据，否则我们就不能胜诉。unless“除非”；once“一旦”；as long as“只要”；since“既然”。根据句意可知C项正确。一、“介词定语从句”中介词的选择及其后关

29、系词的选择(1)介词后的关系代词主要有which和whom。(2)在“介词定语从句”中，介词的选择常常依据下面三点(1)根据语境选介词(2)根据谓语部分的搭配选介词(3)根据先行词选介词In the dark street，there wasnt a single person to whom she could turn for help.在漆黑的大街上没有一个人能为她提供帮助。(to与从句谓语动词构成搭配turn to“求助于”)Recently I bought an ancient vase, the price of which( whose price) was very reas

30、onable.最近我买了个古代的花瓶，它的价钱很合理。高考体验1(2011江西卷)She showed the visitors around the museum, the construction _had taken more than three years.Afor which Bwith whichCof which Dto which答案C句意：她带着游客参观这座博物馆花了三年多才建成的建筑。 the construction of(的建筑)，which指代 the museum。 2(2009陕西卷)Gun control is a subject_Americans have

31、 argued for a long time.Aof which Bwith whichCabout which Dinto which答案C考查定语从句。argue about sth“对展开争论”，由此可知C项正确。二、从句中句子的语序从句一般采用陈述句语序，引导词及其修饰词置于从句句首，但要注意有些时候用倒装。When they will come hasnt been made public.他们什么时候来还没公开。高考体验1(2013新课标卷)“You cant judge a book by its cover，”_Aas the saying goes old Bgoes as

32、 the old sayingCas the old saying goes Dgoes as old the saying答案C考查非限制性定语从句。句意：正如古语所说，“你不能以貌取人”。此处as引导非限制性定语从句，修饰前面的整个句子。2(2011辽宁卷)No matter how_，it is not necessarily lifeless.Aa desert may be dry Bdry a desert may be Cmay a desert be dry Ddry may a desert be 答案B考查句子语序。句意：无论沙漠多么干，它并不一定没有生命存在。首先，how

33、 后面紧跟的应是其修饰的形容词dry，故排除A、C两项；此外，此处要用陈述句语序，故B项正确。一、定语从句与同位语从句的比较判断是定语从句还是同位语从句可以用“加词”的方法，即在名词和从句之间加入一个be动词，如果句子意思成立，则是同位语从句，否则，则是定语从句。试比较：The notice that meeting had to be put off was true.(同位语从句)The notice that he read just now was true.(定语从句)高考体验(2012江苏卷)The notice came around two in the afternoon_t

34、he meeting would be postponed.Awhen Bthat Cwhether Dhow答案B考查同位语从句。分析句子成分可知，“_the meeting would be postponed”是同位语从句，解释说明notice的具体内容，从句句意完整，且不缺少成分，所以用that引导。二、定语从句与状语从句的比较当涉及“地点”时，判断是定语从句还是状语从句的依据：看句中是否有先行词。试比较：Lets have a short meeting where we met last time.(地点状语从句，修饰动词have，表示开会的地方)This is the place

35、 where we had a meeting last time.(定语从句，在句中作定语修饰先行词the place)高考体验1(2013北京卷)Many countries are now setting up national parks _animals and plants can be protected.Awhen BwhichCwhose Dwhere答案D考查定语从句。句意：许多国家现在正在建立国家公园，动植物可以在这里得到保护。where animals and plants can be protected是定语从句，修饰先行词national parks，关系副词wh

36、ere在从句中作地点状语。2(2012天津卷)Everything was placed exactly _he wanted it for the graduation ceremony.Awhile Bwhen Cwhere Dthough答案C考查状语从句。句意：在毕业典礼上，一切东西都放在他想放的位置。此处where引导地点状语从句。三、定语从句与并列句的比较区分定语从句与并列句，要注意句中的标点符号和连接词。如果句与句之间有并列连词and，but或者分号，则是并列句；如果是逗号，且逗号后的内容是对前面内容的补充说明，则是非限制性定语从句，应该使用关系词。试比较：She brought

37、 with her three friends, none of whom I had ever met before.(定语从句)She brought with her three friends, and none of them I had ever met before.(并列句)高考体验(2013重庆卷)John invited about 40 people to his wedding, most of _are family members.Athem Bthat Cwhich Dwhom答案D考查定语从句。句意：约翰邀请了大约四十个人参加他的婚礼，其中大部分是家庭成员。该定

38、语从句的先行词指人，且“most of _”在从句中充当主语，空处位于介词后，故用关系代词whom引导。四、定语从句与强调句的区分区分是定语从句还是强调句，看从句中是否缺少句子成分，如果去掉it is/was和that/who，结构仍完整，则为强调句，反之，则为定语从句。试比较：It was in the hospital that he came across a friend of his.(强调句)It was the hospital where he came across a friend of his.(定语从句)此外，高考时常将定语从句与省略、强调结合起来在具体语境中进行考查，

39、所以，我们在解题时不能只考虑语法，还应注意实际交际功能。如：Where did you get to know her?It was on the farm where we worked.高考体验(2013重庆卷)It was with the help of the local guide _the mountain climber was rescued.Awho Bthat Cwhen Dhow答案B考查强调句。句意：在当地导游的帮助下，这个登山运动员才得以获救。强调句的基本结构为：It is/was被强调部分that/who .五、定语从句中关系代词与关系副词的比较关系代词在定语从句

40、中作主语、宾语、表语和定语；关系副词在定语从句中作状语。注意：先行词是地点名词时，关系词不一定用where；先行词是时间名词时，关系词不一定用when；先行词是reason时，关系词不一定用why。试比较：This is the factory where I worked last year.This is the factory (that/which) I visited last year.I will never forget the day when I worked with them.I will never forget the day (that/which) I spen

41、t with them.This is the reason why he was absent from school.This is the reason (that/which) he explained for his absence from school.以上例句中visit，spend和explain为及物动词，从句中缺少宾语，故应用that/which引导。高考体验1(2013四川卷)Nowadays people are more concerned about the environment _they live.Awhat BwhichCwhen Dwhere答案D考查定

42、语从句。句意：现在人们更加关心他们所居住的环境。分析句子结构可知，空处引导定语从句，先行词为environment，关系词在定语从句中作地点状语，所以用关系副词where。2(2012全国卷)That evening，_I will tell you more about later, I ended up working very late.Athat Bwhich Cwhat Dwhen答案B考查定语从句。句意：那天晚上，我工作到很晚，我以后会告诉你更多相关的情况。which I will tell you more about later是非限制性定语从句，which在从句中作about

43、的宾语，代指that evening。 六、定语从句中as与which的比较(1)as引导的非限制性定语从句放在主句之前、主句之后或者插在主句中间皆可，表示众所周知或意料之中的事；而which引导的非限制性定语从句则只能放在主句之后。(2)当非限制性定语从句的谓语为be announced, be expected, be known, be reported, be said, be shown等被动式谓语时，常用as引导。(3)as表示整个主句内容时，有时含有“正如；正像”等意思，而which无此意。(4)在下列固定结构中，关系代词as代表整个主句所述的内容，一般不用which。例如：as

44、 we know 众所周知as has been said before 如前所述as is often the case 情况常常如此试比较：Li Ming was late for school again, which made Mr. Zhang very angry.You know, as we expected, Li Ming was late for school again.As is known to all, China is in the east of Asia.高考体验1(2013山东卷)There is no simple answer, _is often t

45、he case in science.Aas Bthat Cwhen Dwhere答案A考查定语从句。分析句子结构可知，该题为非限制性定语从句，所填词在从句中作主语。that不能引导非限制性定语从句，where和when不能作主语，所以选as。2(2011北京卷)Mary was much kinder to Jack than she was to the others, _， of course, made all the others upset.Awho Bwhich Cwhat Dthat答案B考查定语从句。which 引导非限制性定语从句，指代整个主句部分的内容。七、定语从句中wh

46、o, whom与whose的比较who在引导的定语从句中作主语，whom作宾语，whose作定语，其中who也可以代替whom作宾语，但who不能位于介词后；who与whom只能指人，whose既可指人又可指物。试比较：He is the only one of the students who has passed the exam.Do you know the man who(m) Mr. Black talked with just now?Do you know the man with whom Mr. Black talked just now?We live in the ro

47、om, whose window faces the south.高考体验1(2013湖南卷)Happiness and success often come to those _are good at recognizing their own strengths.Awhom Bwho Cwhat Dwhich答案B考查定语从句。句意：幸福和成功往往降临到那些善于意识到自己优点的人的身上。先行词是those，关系词在从句中作主语，因此用关系代词who引导定语从句，故答案为B。2(2012天津卷)I wish to thank Professor Smith, without _help I

48、would never have got this far.Awho Bwhose Cwhom Dwhich答案B考查非限制性定语从句。句意：我想感谢史密斯教授，没有他的帮助我不会取得这样的成绩。从句中的help是名词，与Professor Smith是所属关系，故用whose。八、名词性从句中what与that的比较that引导名词性从句时，在从句中不充当任何成分，也没有任何含义；what引导名词性从句时，在从句中要充当一定的句子成分。试比较：What he said made me angry.That he said so made me angry.That we need more

49、time is clear.What we need is more time.高考体验1(2013四川卷)_you said at the meeting describes a bright future for the company.AWhen BHow CWhat DThat答案C考查名词性从句。句意：你在会上所说的话描述了公司的光明前景。分析句子结构可知，空处引导主语从句，且在从句中作宾语，故用what。2(2012江西卷)It suddenly occurred to him_ he had left his keys in the office.Awhether BwhereC

50、which Dthat答案D考查连词。It occurs/occurred to sb that .是固定句型，表示“某人突然想起”。it是形式主语，that引导的从句作真正的主语。九、名词性从句中whether与if的比较whether和if在宾语从句中可以互换，但介词后一般用whether，在其他情况下用whether而不用if。试比较：I wonder whether/if you would like to join us in the outing this weekend.I have no idea whether he will come to help us.Whether

51、you can come or not makes a difference.高考体验(2012天津卷)It doesnt matter_ you turn right or left at the crossingboth roads lead to the park.Awhether Bhow Cif Dwhen答案A考查名词性从句。句意：在十字路口无论你向右转还是向左转都没关系，两条路都通向公园。句中的It是形式主语，whether引导主语从句。whether . or .意为“是还是，不管还是”。十、名词性从句中whichever与whoever及whatever的比较whoever与

52、whatever表泛指，意为“无论谁”，“无论什么”；whichever表示在特定范围内选择，意为“无论的哪一个、哪一些”。试比较：We have plenty of books. You may take whichever you like.Its generally considered unwise to give a child whatever he or she wants.Whichever of them gains the most points wins the competition.Whoever leaves the room last should close t

53、he door.高考体验1(2013江苏卷)_one of you breaks the window will have to pay for it.AWhoever BWhateverCWhichever DWherever答案C考查主语从句。句意：你们中任何一人打破窗户都必须赔偿。根据题干中的one of you可知，此空要用whichever修饰one，指“你们中的任何一个人”。2(2012陕西卷)As many as five courses are provided, and you are free to choose_ suits you best.Awhatever Bwhi

54、cheverCwhenever Dwherever答案B考查宾语从句。句意：提供给你五门功课，你可以自由选择最适合于你的课程。宾语从句中缺少主语，故排除C、D两项。因为前面已提出有五门课程，是有固定范围的，故用whichever。whatever是没有范围的，不符合题意。十一、名词性从句中who与whoever的比较who在名词性从句中表示“谁”；whoever相当于anyone who或those who。试比较：Whoever breaks the law should be punished.Who broke the glass is still unknown.高考体验(2012福建

55、卷)We promise _attends the party a chance to have a photo taken with the movie star.Awho BwhomC.whoever Dwhomever答案C考查连接代词。句意：我们承诺给参加聚会的人一个同电影明星照相的机会。此处考查宾语从句，且从句中缺少主语，故排除B、D两项。whoever 相当于anyone who，强调任何一个人，故选C。十二、名词性从句中why与because的比较why引导名词性从句时意思是“为什么”，可在从句中作主、宾、表、同位语从句；because意思是“因为”，只引导表语从句。试比较：He

56、 was late. Thats because he was stuck in the traffic jam.He was stuck in the traffic jam. Thats why he was late.高考体验(2013安徽卷)From space, the earth looks blue. This is _about seventyone percent of its surface is covered by water.Awhy Bhow Cbecause Dwhether答案C考查名词性从句的引导词。句意：从太空中看，地球是蓝色的。这是因为它表面约百分之七十一

57、都被水覆盖着。此处考查的是表语从句的引导词，主要涉及because和why引导表语从句时的区别。分析前后两句之间的逻辑关系可知，此处为“前果后因”，应用because，故选C。十三、as引导的让步状语从句与although引导的让步状语从句的比较although引导让步状语从句句子为正常语序，而as引导让步状语从句用倒装。试比较：Although he worked hard, he failed in the exam.Hard as he worked, he failed in the exam.高考体验1(2012陕西卷)Hot _the night air was, we slept

58、 deeply because we were so tired after the long journey.Aalthough BasCwhile Dhowever答案B考查倒装句。句意：尽管夜间的空气很热，但我们睡得很沉，因为长途旅行之后，我们太累了。as引导让步状语从句时，从句用倒装语序，其结构为：名词/形容词/副词/动词as主语谓语动词。although与while也可以引导让步状语从句，但它们不能用倒装语序。2(2011天津卷)_regular exercise is very important, its never a good idea to exercise too clo

59、se to bedtime.AIf BAs CAlthough DUnless答案C考查连词。句意：尽管有规律的锻炼是很重要的，但是在临近就寝的时候进行锻炼绝不是一个好主意。根据句意可知，此处是一个让步状语从句，故用 although 引导。十四、时间状语从句中since与before的比较since引导时间状语从句表示“自从以来”，主句常用完成时；before表示“在之前；还未就；还未来得及就”等，常构成句式：It was not long before .，It will be some time before .等。试比较：He hung up before I could explain what had happened.It is three years since he came to work in our school.It w