1、第二部分 基础语法突破引导词用法when从句动作与主句动作可以是同时发生，也可以是先后发生。When he finished writing the report,he went to chat with his parents.写完那份报告后，他就去跟父母聊天了。When my mother cleaned the room,I was washing clothes.我妈妈打扫房间时我正在洗衣服。while从句的谓语动词必须是延续性的，强调主句动作与从句动作同时发生。While they were talking,the bell rang.他们正在谈话的时候门铃响了。当两个延续性动作同时
2、发生且具有对比意味时，常用while。While she was making a call,I was writing a letter.她打电话时，我正在写信。as从句动作与主句动作同时发生。意为“一边一边；随着”。The students took notes as they listened.学生们边听课边做笔记。As you grow older,youll know better and better about yourself.随着年龄的增长，你会越来越了解自己。before意为“在之前；之后才；没来得及就”，常表示主句动作先于从句动作发生。从句一般不为否定句。I must f
3、inish this letter before I go home.我必须在回家之前写完这封信。She died before she wrote a will.她还没来得及写遗嘱就去世了。“It be(not)一段时间before.”结构的肯定句意为“多长时间后才”；否定句意为“用不了多长时间就”。It will be a long time before we buy a house.我们需要很长时间才能买一栋房子。It was not long before the thief was caught.不久小偷就被抓住了。until/till意为“直到”，两者常可互换。主句为肯定句时，谓
4、语须用延续性动词，表示动作一直持续到until所表示的时间为止。I will wait until/till the concert is over.我会一直等到音乐会结束。He stayed there until his teacher came back.他在那里一直待到他老师回来。主句是否定句时，谓语须用非延续性动词，表示主句动作直到until/till所表示的时间才发生。He didnt know anything about it until I told him.直到我告诉他，他才知道这件事。since意为“自从以来”。主句用完成时，从句常用一般过去时从句谓语是延续性动词，表示从
5、这一状态的终止开始。He has written to me frequently since he was ill.自从病好以来他经常给我写信。从句谓语是终止性动词，表示从这一动作开始。He has written to me frequently since he went abroad.自从出国以来他经常给我写信。once意为“一旦”，暗含条件意味。Once you begin,you will never give up.一旦你开始了，就不会放弃。by the time意为“到某一时间点为止”，主句常用完成时态。By the time he graduated,he had done
6、many kinds of jobs.大学毕业之前，他已经做过很多种工作。引导词用法because表示造成某种情况的直接原因。语气最强，常用来回答why的提问。He didnt have breakfast because he got up too late.因为起床太晚了，他没有吃早饭。since表示显然的或已为人知的理由，语气比because弱，通常置于句首。Since you wont help me，I will ask someone else.既然你不肯帮我，我就去问别人了。as表示的原因是已知的事实或显而易见的原因，语气比since更弱。As she has no car,sh
7、e cant get there easily.由于她没有汽车，所以无法顺利到达那里。now that意为“既然”，表示微弱的原因，位于句首时，that可省略。Now(that)you understand,I dont need to explain again.既然你已经明白了，我没有必要再解释一遍。引导词用法so that/in order that意为“为了，以便”。My father works hard in order that he may support us.我父亲为了养家辛苦地工作着。Bring it closer so that I may see it better.
8、把它拿近点儿，让我看仔细。in case(that)/for fear that意为“以防，万一，以免”。He told us to keep quiet for fear that we might disturb others.他让我们保持安静，以免打扰别人。Take the raincoat in case it may rain.带着雨衣以防下雨。引导词意义常用结构so.that.意为“如此以致”so形容词/副词thatHe drove so carelessly that he almost lost his life.他开车太大意了，差点儿丢了性命。so形容词a(n)可数名词单数t
9、hatIt was so good an exhibition that I went to see it several times.那个展览非常好以至于我去看了好几次。so.that.意为“如此以致”somuch/little(少的)不可数名词thatHe got so little money that his family had to live on welfare.他挣钱很少，他的家人不得不靠救济生活。such.that.意为“如此以致”sucha(n)形容词可数名词单数thatShe is such a good teacher that everyone admires her
10、.她是个好老师，每个人都敬重她。such形容词可数名词复数thatThey are such honest girls that we all trust them.这些女孩是如此诚实，我们都很信任她们。such形容词不可数名词thatIt is such nice weather that I dont like to stay at home.天气这么好，我不想待在家里。引导词用法though/although两者可以换用，但although更正式。强调对比性时，主句可用yet或still引出，但不可用but。Although/Though she works very hard，she
11、makes very slow progress.尽管她非常努力，但还是进步很慢。even if/even though表示语气更强的让步，意为“尽管，即使，退一步说”。We will make a trip even if/even though the weather is bad.即使天气不好，我们也要去旅行。as引导让步状语从句时，从句中的表语、状语以及谓语中的实义动词需提前至句首，作表语的单数可数名词前如有冠词，冠词需要省去。Child as he was，he knew what was the right thing to do.尽管他还是个孩子，但他知道做什么事情是对的。Obj
12、ect as you may，Ill go.即使你反对，我也要去。引导词用法if意为“如果”。If he breaks his promise,she will never speak to him again.如果他不遵守诺言，她就再也不理他了。unless意为“除非，如果不”，相当于if.not.You wont pass the exam unless you study hard.如果你不努力学习，就不能通过这次考试。Unless you visit him tomorrow,hell be angry.除非你明天去看他，否则他会生气的。as/so long as意为“只要”。As/So long as we dont lose heart,we will find a way to overcome difficulty.只要不灰心，我们就能找到克服困难的办法。on condition that意为“在条件下”。You can go swimming on condition that you dont go too far from the river bank.你只要不远离河岸就可以去游泳。