高中英语-定语从句、状语从句和同位语从句知识点总结

中考复习专题状语从句知识点总结及经典习题(含答案)

中考复习专题状语从句知识点总结及经典习题(含答案) 一、初中英语状语从句 1． the journey was tiring，Jeff thought it was worth both the time and the money. A．As B．Since C．Unless D．Although 【答案】D 【解析】【详解】句意：虽然旅途很累，杰夫认为时间和金钱都值得。 A. As当……的时候； B. Since 自从； C. Unless除非； D. Although尽管。根据下文Jeff thought it was worth both the time and the money.可知上文是让步状语从句，这里用Although引导。根据题意，故选D。 2．--- I wonder if Tina to China next week. --- If it ，she will come. A．will come；won’t rain B．comes；doesn’t rain C．comes；won’t rain D．will come；doe sn’t rain 【答案】D 【解析】【详解】句意：——我想知道蒂娜下周是否会来中国。——如果不下雨，她就会来。根据语境推测对话的语境是“——我想知道蒂娜下周是否会来中国。——如果不下雨，她就会来。”，第一个设空处的if意思是“是否”，引导宾语从句，主句是一般现在时，从句根据时间状语next week确定用一般将来时，一般将来时的构成是：主语+will+动词原形，排除B/C；第二个设空处考查含有if引导的条件状语从句中主句的时态，在含有条件状语从句中的复合句中，时态遵循“主将从现”的原则，即：主句用一般将来时，从句使用一般现在时表将来，表示“不下雨”应借助于助动词does，故选D。 3．You are sure to fail the exam ________ you study hard. A．if B．unless C．since D．that 【答案】B 【解析】试题分析：句意：如果你不努力学习，你一定会考试不及格的。A.if如果；B. unless如果不；C. since自从；结合句意，故选B。考点：考查连词的用法。 4．--Where is the comic book? --I brought it to you ________you were in the reading room yesterday. A．when B．if C．because D．before 【答案】A

高中英语状语从句讲解汇总

高中英语状语从句讲解汇总原因从句除了下面A2，A3中所示各种类型外，这两种从句均可由as或because来引导。但是用as引导原因从句较为稳妥（参见A）；用because引导结果／原因从句较为稳妥（参见B）。 A 原因从句 1 由as／because／since 引导的原因从句： We camped there as／because／since it was too dark to go on．我们在那里露宿是因为天太黑，不能再继续往前走了。 As／Because／Since it was too dark to go on，we camped there． [ 因为天太黑不能再继续往前走，我们就在那儿露宿了。 2 in view of the fact that可用as／since／seeing that来表示，但不能用because： As／Since／Seeing that you are here，you may as well give me a hand．既然你在这儿，你就帮我个忙吧。 As／Since／Seeing that Tom knows French，he’d better do the talking．既然汤姆懂法语，最好让他来谈。 3 在as／since／seeing that意指以前共知的或共知的陈述时，可用if来代替： ~ As／Since／Seeing that／If you don’t like Bill，why did you invite him 既然／如果你不喜欢比尔，你为什么邀请了他注意：if so的用法： —I hope Bill won’t come． —If so（＝If you hope he won’t come），why did you invite him —我希望比尔别来。 —如果这样（=如果你希望他不来），你为什么邀请了他关于if＋so／not，参见第347节。 ~ B 结果从句由because或as引导： The fuse blew because we had overloaded the circuit．保险丝烧断了，因为我们使线路超载了。 He was angry because we were late．他生气是因为我们来晚了。 As it froze hard that night there was ice everywhere next day．因为那天晚上冷得厉害，所以第二天到处都是冰。 ~ As the soup was very salty we were thirsty afterwards．因为这汤很咸，后来我们渴得厉害。

【英语】状语从句知识点总结

【英语】状语从句知识点总结一、初中英语状语从句 1．---Can students go online during lessons? ---They can’t ________ it is for that lesson. A．if B．unless C．until D．while 【答案】B 【解析】【详解】句意：——学生上课时能上网吗？他们不可以，除非为了上那堂课。本题考查连词辨析，A.如果；B.除非；C.直到；D.当……时候。答语是条件状语从句，根据句意结构可知，需要unless连接，故选B。 2．Tony has had to cook by himself ________ his mother went on business to Guangzhou. A．since B．after C．during D．when 【答案】A 【解析】【详解】句意：自从妈妈去广州出差以来，托尼不得不自己做饭。A. since从……以来；B. after在……之后；C. during 在……期间；D. when当……时候。since后跟时间状语从句时，表示的是到目前为止的时间段，从句时态为一般过去时，而主句的时态为现在完成时，故正确答案为A。 3．—____ the workers are very tired, _____they keep on working. — They are great. We must learn from them. A．Because; / B．Though; / C．Because; so D．Though; but 【答案】B 【解析】试题分析：句意：尽管工人们很累了，但他们仍然继续工作。——他们太伟大了，我们应该向他们学习。本题考查连词的用法。Because用于表示因果关系，不能与so同时使用；Though用于表示转折关系，不能与but同时使用。结合句意，故选B. 考点：考查连词的用法。 4．Chen Wei isn’t at school today ________ he is taking a robot competition in Shanghai. A．so B．because C．before D．if

高中英语语法定语从句总结全

高中英语定语从句详解 Ⅰ、概念: (１) 定语从句:在主从复合句中用作定语得从句叫定语从句。定语从句一般紧接在先行词（antｅcedｅｎt)后面。 (2) 先行词:被定语从句修饰得成份。先行词可以为一个词,短语，或整个主句。 (3)引导定语从句得词叫关系词,分为关系代词与关系副词。关系词得作用: 1) 引导定语从句，连接主句与从句,相当于一个连词; ２) 必在从句中作某个句子成份(可以做主语,宾语,表语,定语，状语) 常用得关系代词: ｔhat、wｈｉcｈ、wｈo、whom、wｈosｅ,当关系代词在定语从句中做宾语时，关系代词可以省略。常用得关系副词(在从句中只作状语): when(时间状语）、why(原因状语)、wｈe ｒｅ（地点状语）可以修饰人得关系代词:thａt, ｗho，wｈｏｍ,whosｅ可以修饰事得关系代词:tｈat, whｉcｈ, as，whose, The studeｎt who answerｅd ｔhe ｑuestion was John、Ｉkｎow thｅｒeasoｎwhy he wａｓso angｒy、 The bｏy （wｈom) ｙou are taｌkｉnｇｔo is myｂrotｈｅｒ、Ｉ'd likｅ a ｒoｏｍwhose window fａｃesｔｈe sea、定语从句三步：第一找出先行词; 第二瞧先行词在定语从句中得语法功能（做主语、宾语、表语或状语); 第三选择合适得关系词。 Ⅱ、几个关系代词得基本用法: ●tｈat:可指人或物；在定语从句中作主语,宾语,表语。(指人时,相当于whｏ或wｈｏｍ;指物时,相当于whiｃh)（一般不用于非限制性定语从句；不可置于介词后作宾语) 如: 1、A lｅtteｒthaｔ／which is wrｉtｔen in peｎcｉl is diffiｃult ｔo ｒead、（主语) 2、Do yｏu kｎｏw tｈe gentleman ｔhａｔ/ｗｈｏspoke just ｎｏw? 3、Ｙou can takｅａnything ( ｔhat)you like、(宾语) 4、Whaｔｉs thｅquestiｏｎ(ｔhat/whｉｃh) they aｒｅｔalｋing about? 5、Hｅreｉs theｍan （wｈo／whom/ｔhat) yｏu want tｏsee、 6、Ｓhe＇s no longeｒthe girl( that) sｈeｕsｅd to ｂe befｏre、（表语） 7、Ｏuｒhometｏwn iｓno ｌonger ｔhｅoｎe (thａt)it usｅｄto ｂe、(=Ｏｕr homeｔｏｗn iｓｎot tｈe sａｍe as it uｓed tｏｂe、 = Our hｏmｅtｏwn is diffeｒenｔfrom what iｔｕｓｅｄtｏｂe。 =Ouｒhometｏｗn ｉs notｗhａt it uｓed to ｂe、) ●which：指物;在定语从句中作主语,宾语。如： 1、Thｅboｏk which/thａｔwas ｏn the ｄeｓkｗａsｂought bｙｍy fatｈer、(主语) 2、Tｈｅboｏk(whiｃh/tｈaｔ) Ｉｂｏught yesteｒdaｙｉs very

高中英语状语从句100题

状语从句暑假练习一 1.___ hard he tries, he never seems able to do the work successfully. A. Whatever B. However C. Whichever D. Whenever 2.We have to be patient. It will be some time ___ we get the full result. A. since B. that C. before D. after 3.She lied to us ___ she had to ___ a job. A. what; to get B. because; get C. because; in order get D. all; get 4.I was about to go out ___ the telephone rang. A. then B. when C. suddenly D. so 5.This equipment is so old ___ it can’t be used any more ___ some o f its parts are changed. A. as; unless B. that; unless C. that; if D. whether; or 6.I’ll tell you the result of the test ___ I know it. A. because B. the moment C. though D. for 7.You can’t go out to play ___ you finish your homework. A. if B. because C. unless D. when 8.I was late today ___ there was something wrong with my bike. A. since B. as long as C. because D. when 9.You can’t waste natural resources ___ you have much of them. A. as if B. even if C. when D. if 10.Please speak clearly ___ we can follow you. A. s o…that B. so C. so as to D. so that 11.___ you have made a decision, don’t change it frequently. A. Once B. Before C. While D. Even if 12.He used to tell children the story ___ he had had the experience. A. as though B. even if C. even though D. like 13.He came to help us ___ he had plenty of work to do. A. as B. while C. although D. whenever 14.___, he knows how to live and study. A. A child as he is B. As he is a child C. Child as he is D. Though he is child 15.We found people friendly ___ we went. A. to which B. in which C. wherever D. to where 16.___ the weather is fine, I’ll open all the windows. A. Now that B. Since that C. Because of D. For 17.It was ___ he couldn’t finish it by himself. A. so difficult a work as B. such a difficult work as C. so difficult work as D. such difficult work that 18.___ I know, this book will be used as a text book. A. So far as B. So far C. So long as D. As to 19.He had disappeared in the darkness ___ I saw who he was. A. before B. after C. till D. while 20.We’ll build a power station ___ water resour ces are plentiful. A. where B. in which C. which D. that 21.___ we don’t lose heart, we’ll find a way to overcome the difficulty.

状语从句知识点讲解.

状语从句一. 时间状语从句常用引导词:when, as, while, as soon as, before, after, since , till, until, 特殊引导词:the minute, the moment, the second, every time, the day, the instant, immediately , directly, no sooner … than, hardly … when, scarcely … when I didn’t realize how special my mother was until I became an adult. While John was watching TV, his wife was cooking. The children ran away from the orchard(果园 , the moment they saw the guard. (一 . when, while和 as 的区别 (1 when 引导的从句的谓语动词可以是延续性的动词, 又可以是瞬间动词。并且 when 有时表示“就在那时” 。 When she came in, I stopped eating.她进来时,我停止吃饭。 (瞬间动词 When I lived in the countryside, I used to carry some water for him.当我住在农村时,我常常为他担水。 (延续性的动词 (2 While 引导的从句的谓语动词必须是延续性的, 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 (3 6. when 和 while 都可表示“当 ..... 时.... ” “这时候..... ” when 后及短暂性动词 (land , come in , meet , leave 等 , while 后及延续性动词(shop , visit , read , sleep 等 when 后接一般过去式。

(完整版)高中英语定语从句讲解及练习

高中英语定语从句讲解及练习定语从句是高中重点知识，也是高考常考点，大家也不容易掌握，这篇文章主要教你关系代词引导的定语从句关系副词引导的定语从句判断关系代词与关系副词限制性和非限制性定语从句等内容，有例题讲解定语从句在句中做定语，修饰一个名词或代词，被修饰的名词词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。关系代词有：who, whom, whose, that, which等。关系副词有：when, where, why等。 18.1 关系代词引导的定语从句关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。 1）who, whom, that 这些词代替的先行词是人的名词或代词，在从句中作主语和宾语。例如： Is he the man who/that wants to see you? 他就是你想见的人吗？（who/that在从句中作主语） He is the man whom/ that I saw yesterday. 他就是我昨天见的那个人。（whom/that在从句中作宾语） 2）whose 用来指人或物，（只用作定语, 若指物，它还可以同of which互换）。例如： They rushed over to help the man whose car had broken down.那人车坏了，大家都跑过去帮忙。 Please pass me the book whose （of which）cover is green.请递给我那本绿皮的书。 3）which, that所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等。例如： A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未有的繁荣。（which / that在句中作宾语） The package （which / that）you are carrying is about to come unwrapped. 你拿的包快散了。（which / that在句中作宾语） 18.2 关系副词引导的定语从句关系副词可代替的先行词是时间、地点或理由的名词，在从句中作状语。 1）关系副词when, where, why的含义相当于\"介词+ which\"结构，因此常常和\"介词+ which\"结构交替使用。例如： There are occasions when （on which）one must yield.任何人都有不得不屈服的时候。 Beijing is the place where（in which）I was born.北京是我的出生地。 Is this the reason why （for which）he refused our offer?这就是他拒绝我们帮助他的理由吗？ 2）that代替关系副词，可以用于表示时间、地点、方式、理由的名词后取代when, where, why和\"介+which\"引导的定语从句，在口语中that常被省略。例如： His father died the year （that / when / in which）he was born.他父亲在他出生那年逝世了。 He is unlikely to find the place （that / where / in which）he lived forty years ago. 他不大可能找到他四十年前居住过的地方。 18.3 判断关系代词与关系副词方法一：用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要求用关系代词；而不及物动词则要求用关系副词。例如： This is the mountain village where I stayed last year. 这是我去年呆过的山村。 I'll never forget the days when I worked together with you.我永远不会忘记与你共事的日子。判断改错：（错）This is the mountain village where I visited last year. （错）I will never forget the days when I spent in the countryside. （对）This is the mountain village （which）I visited last year. （对）I'll never forget the days （which）I spent in the countryside. 习惯上总把表地点或时间的名词与关系副词where, when联系在一起。此两题错在关系词的误用上。方法二：准确判断先行词在定语从句中的成分（主、谓、宾、定、状），也能正确选择出关系代词/关

状语从句知识点总结和题型总结

状语从句知识点总结和题型总结一、初中英语状语从句 1．—Have you heard of the latest news about WIFI? —Yes. When the 5G age , the Internet speed will be 100 times as high as 4G. A．come B．comes C．will come D．is coming 【答案】B 【解析】【详解】句意：——你听说过无线网络的最新消息吗？——是的。到了5G时代，网速将是4G的100倍。A. come动词原形； B. comes第三人称单数形式； C. will come一般将来时态； D. is coming现在进行时态，此句是when引导的时间状语从句，遵循主将从现的原则，此空应填谓语动词的第三人称单数形式，此空故填comes。 2．The Italian woman didn’t feel a culture shock____it was her first time to Shanghai. A．though B．since C．if D．when 【答案】A 【解析】句意：这个意大利妇女没有感到一种文化冲击，尽管她是第一次来上海。A. though尽管； B. since自从； C. if 是否，如果； D. when当---时候；根据The Italian woman didn’t feel a culture shock这个意大利妇女没有感到一种文化冲击，和it was her first time to Shanghai.她是第一次来上海之间用though 引导让步关系状语从句；故选A 3．___________ she couldn’t see his face, she could tell by his voice that he was young. A．Unless B．If C．Because D．Though 【答案】D 【解析】【详解】句意：虽然她看不见他的脸，但是她能够通过声音分辨出他很年轻。A. Unless除非；B. If 如果；C. Because因为；D. Though尽管。根据语境以及上下文，本题考查的是连词的用法。结合句意可知，在这里两个句子之间存在一个相反的让步关系，though/although/even though"虽然；尽管"，引导让步状语从句，符合句意。故答案选D。 4．— What were you doing ______ I knocked at the door? — I was sleeping. A．unless B．once C．when D．while 【答案】C 【解析】

状语从句知识点(大全)经典

状语从句知识点(大全)经典一、初中英语状语从句 1．—Have you heard of the latest news about WIFI? —Yes. When the 5G age , the Internet speed will be 100 times as high as 4G. A．come B．comes C．will come D．is coming 【答案】B 【解析】【详解】句意：——你听说过无线网络的最新消息吗？——是的。到了5G时代，网速将是4G的100倍。A. come动词原形； B. comes第三人称单数形式； C. will come一般将来时态； D. is coming现在进行时态，此句是when引导的时间状语从句，遵循主将从现的原则，此空应填谓语动词的第三人称单数形式，此空故填comes。 2．Tony has had to cook by himself ________ his mother went on business to Guangzhou. A．since B．after C．during D．when 【答案】A 【解析】【详解】句意：自从妈妈去广州出差以来，托尼不得不自己做饭。A. since从……以来；B. after在……之后；C. during 在……期间；D. when当……时候。since后跟时间状语从句时，表示的是到目前为止的时间段，从句时态为一般过去时，而主句的时态为现在完成时，故正确答案为A。 3．I didn't realize he was a famous scientist you told me. A．until B．because C．since 【答案】A 【解析】句意：直到你告诉我，我才知道他是一位出名的科学家。A. until到…为止；B. because 因为；C. since既然，因为。本题考查固定句式not…until…直到……才。其用法是如果（主）句中的谓语是终止性动词，应采用“not…until”结构，意为“到……时候才” 根据句子结构，结合选项，故选A。 4．________it’s Sunday tomorrow, we have to go to school. A．Though B．Since C．As D．Because

高一英语定语从句讲解精华版

定语从句一、基本概念：定语：定语从句： Do you know the man who spoke at the meeting just now That is the house where he lived ten years ago. 引导词：关系词关系代词有：that, who, whom, whose, which; 在从句中充当：关系副词有：when, where, why. 在从句充当：先行词：定语从句中引关系词的作用：二、关系词的用法：（一）关系代词的用法： 1． He is the man lives next door. The train has just left is for Shenzhen. 2． The man ________ we have just seen is a famous writer. Where is the book ___________I bought last week （二）关系副词的用法： 1． I still remember the time ________I first became a college student. Do you know the date __________Lincoln was born

(三) 使用关系副词应注意下列几点： 1．这三个关系副词在意义上都相当于一定的介词+which结构： when = on (in, at, during…) + which; where = in (at, on…) + which; why = for which. 如： I was in Beijing on the day when (=on which) he arrived. The office where (=in which) he works is on the third floor. This is the chief reason why (=for which) we did it. 2．当先行词是表时间的time, day等和表地点的place, house等时，一定要注意分析从句的结构，如果缺少主语或宾语时，关系词应该用which或that, 缺少时间状语或地点状语时，才能用when或where，试比较： I’ll never forget the day _________ my hometown was liberated. I’ll never forget the days____________we spent together last summer. His father works in a factory____________radio parts are made. His father works in a factory______________makes radio parts. 三．限制性定语从句与非限制性定语从句 1．限制性定语从句 This is the telegram which he refers to. Is there anything (that) I can do for you 2．非限制性定语从句 This note was left by Tom, who was here a moment ago. As a boy, he was always making things, most of which were electric.

高中英语状语从句讲解

高中状语从句讲解+练习状语通常由副词、介词短语、动词不定式、分词和从句等担当。例如： 1. Naturally , our grandparents were pleased to get our phone call . (副词) 2. We worked hard , from sunrise to sunset . (介词状短语) 3. To help my disabled aunt , I spend an hour working in her house every day . (不定式) 4. Seen from a distance , the farmhouse looked deserted . (过去分词) 5. I know how to light a camp fire because I had done it before .（原因状语从句）状语从句主要用来修饰主句或主句的谓语。一般可分为九大类，尽管种类较多，但由于状语从句与汉语结构和用法相似，所以理解和掌握它并不难。状语从句的关键是要掌握引导不同状语从句的常用连接词和特殊的连接词即考点。现分别列举如下: 1．时间状语从句常用引导词：when, as, while, as soon as, while, before, after, since , till, until 特殊引导词：the minute, the moment, the second, the instant, immediately , directly, every time, the day，no sooner …than, hardly …when, scarcely …when （1）Tell him I need to see him the minute he arrives. 他一到就告诉他我要见他。（2）The children ran away from the orchard(果园) the moment they saw the guard. The moment he saw me, he ran away. 他一看见我，就跑了。 He said he’d call you the moment he got home. 他说他一到家就给你打电话（3）The instant I saw him, I knew he was the man from the restaurant. （4）Immediately you begin to speak, he gives you his full attention.你只要一开始说话，他就全神贯注地听。（5）My sister came directly she got my message. 我妹妹一收到我的信息就来了。（6）Every time I listen to your advice, I get into trouble. （7）no sooner... than... ，"一...就..." ，引导时间状语从句,主句用过去完成时,"than"后面的从句用一般过去时.(从这里可以知道,no sooner后面是主句;than后面是从句) 例: I had no sooner reached home than it began to rain. 我一到家天就下起雨来 No sooner ...than...常放在句首,表示强调.这时主句要倒装. 例:No sooner had I reached home than it began to rain. （8）He had hardly sat down when the telephone rang.他刚坐下电话就响了。 He had scarcely sat down when there was a knock at the door. 他刚坐下就有人敲门另外，如果把hardly放于句首，主句要用倒装结构。如： Hardly had I finished eating when he came in. 我刚吃完他就进来了。 2．地点状语从句常用引导词：where 特殊引导词：wherever, anywhere, everywhere Generally, air will be heavily polluted where there are factories. She was standing exactly where you are standing now那时他就站在你现在站的地方。 Stay where you are.呆在原地别动。 Wherever you go, you should work hard. Sit anywhere you like 随便坐吧 3．原因状语从句

第五讲-高中英语状语从句详解

状语从句一：状语从句的定义、功能、分类定义：在复合句中作状语的从句功能：状语从句在主从复合句中修饰主句中的动词，形容词或副词，或整个主句分类：按意义可分为时间、地点、原因、目的、结果、条件、方式、比较、让步等状语从句。位置：从句的位置放在句首，也可放在句末。放在句首时，从句后面常用一个逗号，放在句末时，从句前一般不用逗号。二：考点与难点 1、各种从属连词的含义及用法比较； 2、no matter wh- 与wh-ever 引导的从句的区别； 3、状语从句的时态问题； 4、状语从句倒装及省略； 5、状语从句与其它从句的区别。三：九种常见状语从句用法 1. 时间状语从句引导时间状语从句的从属连词 1）.基本类：before、after、when、while、as、since、till、until、once, as soon as, etc. 2）. 名词类 the moment ,the minute, the second, the instant,etc. (一…就…); every time, each time, the last time, the first time, the day, the year, the morning etc. 3）. 副词类：immediately, directly, instantly, etc. (一...就...) 4）.句型类：no sooner…than…, hardly/scarcely…when…, etc. (一…就…) 注意：1. when, as, while When ①when表示时间点时，从句中用短暂性动词；表示时间段时，用持续性动词。Eg:. When they were still talking and laughing, the teacher came in. （when表示段时间） 2). He waved a hello when he saw her.（when表示点时间） ②. 可用作并列连词，其意义为“这时,突然”，相当于and then suddenly。常用于下列句式： be doing / be about to do sth/ be on the point of doing / have/had done + when Eg.1). I was about to go out when the door bell rang. 2). One evening I was having my dinner when an unexpected friend knocked my door. ③. 还可以表示原因,意思是“既然”，相当于since; considering that Eg. 1). It was foolish of you to take a taxi when you could easily walk there in five minutes . 2). How can he get good grades when he won't study? While ①while通常表示一段时间，从句中常用持续性动词作谓语。 Eg: Strike while the iron is hot. 趁热打铁。 ②while有时可以作并列连词，表示对比，可译成“然而……”。 Eg: 1). I am fond of English while he likes maths. ③while有时可引导让步状语从句，意思是“虽然”。 Eg. While they love the children, they are strict with them. As ①表示一边……一边……，强调从句和主句中两个动作交替进行或同步进行。 eg: She is singing a song as she took a bath. ②as表示随着 eg: As time goes on, it's getting warmer and warmer. 2. till, until和not…until 1）until /till用于肯定句时，表示直到…为止，主句必须为持续性动词。

高中英语-定语从句、状语从句和同位语从句 知识点总结