欢迎来到淘文阁 - 分享文档赚钱的网站! | 帮助中心 好文档才是您的得力助手!
淘文阁 - 分享文档赚钱的网站
全部分类
  • 研究报告>
  • 管理文献>
  • 标准材料>
  • 技术资料>
  • 教育专区>
  • 应用文书>
  • 生活休闲>
  • 考试试题>
  • pptx模板>
  • 工商注册>
  • 期刊短文>
  • 图片设计>
  • ImageVerifierCode 换一换

    第03讲-词性和句子成分 2022年初高中英语无缝衔接讲义20讲+精练(解析版)公开课.docx

    • 资源ID:63275992       资源大小:40.53KB        全文页数:15页
    • 资源格式: DOCX        下载积分:15金币
    快捷下载 游客一键下载
    会员登录下载
    微信登录下载
    三方登录下载: 微信开放平台登录   QQ登录  
    二维码
    微信扫一扫登录
    下载资源需要15金币
    邮箱/手机:
    温馨提示:
    快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
    如填写123,账号就是123,密码也是123。
    支付方式: 支付宝    微信支付   
    验证码:   换一换

     
    账号:
    密码:
    验证码:   换一换
      忘记密码?
        
    友情提示
    2、PDF文件下载后,可能会被浏览器默认打开,此种情况可以点击浏览器菜单,保存网页到桌面,就可以正常下载了。
    3、本站不支持迅雷下载,请使用电脑自带的IE浏览器,或者360浏览器、谷歌浏览器下载即可。
    4、本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰。
    5、试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。

    第03讲-词性和句子成分 2022年初高中英语无缝衔接讲义20讲+精练(解析版)公开课.docx

    第03讲词性和句子成分词类又叫词性,英语单词根据其在句子中的功用,可以分成十个大类。1 .名词 noun n. student 学生. 代词 pronoun pron. you 你2 . 冠词 article art. a 一个.数 i司 numeral num. three 三3 .形容词 adjective adj. happy 高兴的.副词 adverb adv. quickly 迅速地4 .动词verb v. cut砍、割. 连词 conjunction conj. and 和5 . 介词 preposition prep. at 在.感叹词 interjection interj. oh 哦前六类叫实词,后四类叫虚词。下面就一一介绍01名词及其基本用法定义:表示人或事物名称的词叫名词。名词分类名词复数的规那么变化名词专有名词普通名词个体名词可数名词集体名词物质名词不可数名词抽冢名词着,on to到上面,onto至lj上面,up向上,away from 远离 时间介词about大约,after在以后,at在(时刻),before在以前,by到为止,during在 期间,for有.(之久),from从(时)起,in在(上/下午),在(多久)以后,on在(某日),past 过了.(时),since自从.(至今),through贯穿.(期间),till直到时,until直到时, to到1(下一时刻),ever since从那时起至今,at the beginning of在开始时,at the end of在 末,in the middle of 在当中,at the time of 在,.时方式介词as作为/当作,by用/由/乘坐/被,in用.(语言),like与一样,on骑(车)/徒(步),通过 (收音机/电视机),over通过(收音机),through通过,with用(材料),用(手/脚/耳/眼),without 没有涉及介词about关于,except除了.,besides除了还for对于/就而言,in在.(方面),of.的, 有关,on关于/有关,to对而言,towards针对,with就而言其它介词目的介词:for为了,from防止,to为了原因介词:for因为,with由于because of因为比拟介词:as与一样,like象一样,than比,to与相比,unlike与不同句子成分(一)句子成分的定义:构成句子的各个局部叫做句子成分。句子成分有主要成分和次要成分;主要成分有主语和谓语;次要成分有表语、宾语、定语、状语、补足语、同位语和插入语。1 .主语主语是一个句子所表达的主体,说明句子里所谈的是:“什么人”或“什么物",一般位于句首。 但在there be结构、疑问句(当主语不是疑问词时)和倒装句中,主语位于谓语、助动词或情 态动词后面。主语可由名词、代词、数词、不定式、动名词、名词化的形容词和主语从句等 表示。如:Since the 1990s, American country music has become more and more popular(名词)自从 20 世 纪90年代以来,美国乡村音乐已经变得越来越流行。They often speak English after class.(代词)Twenty years is a short time in history,数词)To swim in the deep river is a great pleasure.(不定式)Eating too much does harm to your health.(动名词)The rich should help the poor.(名词化的形容词).What he needs is a book.(主语从句)It is necessary for us to master a foreign language(it作形式主语,真正的主语为后面的不定式) 掌握一门外语对我们来说是必要的。It is very clear that the elephant is round and tall like a tree(It 形式主语,that 引导的主语从句是 真正主语大象像树一样又圆又高,这一点是显然的。2 .谓语谓语说明主语所做的动作或具有的特征和状态。说明主语“做什么”“是什么”或“怎么样”。动 词在句中作谓语,一般放在主语之后(在倒装语序下,谓语可放于主语之前)。谓语的构成如 下:简单谓语:由一个动词或动词短语构成。如:She practises running every morning.(单个动词 practise 做谓语)复合谓语由情态动词或其他助动词加动词原形构成。如:You may keep the book for three weeks.(情态动词 may+动词原形 keep 做谓语)The little girl has caught a bad cold.(助动词 hast 动词过去分词 caught 做谓语)由系动词加表语构成。如:We are students now.(系动词are+名词students构成系表结构做谓语)【注意】谓语和主语在人称和数方面必须保持一致。如:I am reading.You are reading.He/She is reading.We are reading.Mary loves swimming.You don't trust me.He believes me.3 .表语表语用以表述说明主语的身份、特征和状态,说明主语“是什么”或“怎么样”,它一般位于 系动词(如be、become> get、look、grow、turn、seem等)之后,与系动词共同构成谓语。 表语一般由名词、代词、形容词、分词、数词、不定式、动名词、介词短语、副词及表语从 句表示。如:Our foreign teacher is an American.(名词)Are they yours?(代词)(They are yours.)The weather has turned warm.(形容词)The lecture is exciting.(分词)Three times seven is twenty-one.(数词)三乘七等于二H。Her job is to teach English.(不 定式)Her hobby is singing popular songs.(动名词)The old machine must be out oforder.(介词短语)这台老机器肯定运转不畅。Time is up. Class is over.(副词)The truth is that she has never been abroad.(表语从句)事实是她从没去过国外。4 .宾语宾语表示动作行为的对象或承受者。由名词、代词或相当于名词或代词的词或短语充当,和 及物动词一起构成谓语,说明主语“做什么”。如:He went to see a film yesterday.(名词)The thick fog prevented us from coining to school on time.(代词)浓雾使我们无法准时到校。How many books do you have? -I have fifty.(数词)We helped the old with their housework.(名词化形容词)She pretended not to see me.(不定式短 语)He enjoys listening to popular songs.(动名词短语)We think (that) she is fit for her job.(宾语从 句)宾语种类:直接宾语和间接宾语-有些及物动词可以有两个宾语,一个指人,一个指物,指人的通常为 动词的间接承受者叫作间接宾语,指物的通常为动词的直接承受者叫直接宾语,在一起称为 成为双宾语,一般间接宾语在前,直接宾语在后,如:He gave me some ink.他给了我一些墨水。间接宾语直接宾语Our teacher told us an interesting story.老师给我妈讲 了一个有趣的故事。间接宾语直接宾语.宾语补足语英语中有些及物动词,除有一个直接宾语以外,还要有一个宾语补语,才能使句子的意义完 整。宾语和它的补足语构成宾语复合宾语。带有宾语补足语的一般句型为:某些及物动词(如 make等)+宾语+宾补。宾补可由名词、形容词、副词、不定式、分词、介词短语和从句充 当。如:His father named him Jack.谓语 宾语 宾补(名词)He painted his wall yellow.(形容词)Let the dog out.(副词)You mustnft force her to lend her money to you.(不定式短语)你不能强迫她借钱给你。We saw him entering the room.(现在分词)He found everything in the lab in good order.谓语定语(修饰everything)(介词短语)We will soon make our school what your school is now.(从句)我们不久就要把我们的学校开展成你们学校目前的那个样子。5 .定语修饰名词或代词的词、短语或从句称为定语。可以作定语的除形容词外,还有名词、代词、 数词、介词短语或相当于形容词的词或短语等。如:Hangzhou is a beautiful city.(形容词)China is a developing country while the USA is a developed country(分词)中国是个开展中国家,而美国是个兴旺国家。There are thirty men teachers in our school.(名词)Her progress in English made us surprised.(代词)Our monitor is always the first to enter the classroom.(不定式短语)我们班长总是第一个进教室 的人。Our teaching plan for the next term has been worked out.(动名词)He is reading an article about how to learn a foreign language.(介词短语)他正在读一本关于如何学外语的书。6 .状语修饰动词、形容词、副词或整个句子,说明动作或状态特征的句子成分,叫做状语。可以作 状语的主要是副词、介词短语或相当于副词的词或短语等。如:Light travels most quickly.(副词及副词性词组)We have lived in the city for ten years.(介词短语)She is proud to have passed the examination.(不定式短语)The boy is in the room making a model plane.(分词短语)Once you begin,you must continue.(状语从句)状语的种类如下:How about meeting again at seven?(时间状语)Last night she didn't go to the party because of the heavy rain.(原因状语).We shall go there if it doesn't rain.(条件状语)Mrs.Green lives on the third floor.(地点状语)He put the eggs into the basket with great care.(方式状语)He came in with a book in his hand.(伴随状语)手上拿着本书,他进来了。In order to catch up with the others, we must work harder.(目 的状语)She was so tired that she fell asleep immediately.(结果状语)Tu Youyou works very hard though she is old.(让步状语)I am taller than she is.(比拟状语)7 .同位语把一个名词(短语)、代词或从句放在另一名词或代词后,对前面的名词或代词作进一步解释, 用以说明前者的性质或情况,这样的名词或代词叫同位语。如:We Chinese people love peace.(Chinese people 是主语 We 的同位语)You all should be punished4代词做同位语)She herself went there.(反身代词做同位语)Our English teacher, Mr. Zhang, is very thin.(名词做同位语)Doctor Li, a kind and friendly girl, lives next to me.(名词短语做同位语)李医生,一个善良又待 人友好的女孩儿,住在我家隔壁。学检测训练一、指出以下句子划线局部是什么句子成分:1. The students got on the school bus.2. He handed me the newspaper.1.1 shall answer your question after class.4. What a beautiful Chinese painting!5. They went hunting together early in the morning.6. His job is to train swimmers.7. He took many photos of the palaces in Beijing.8. There is going to be an American film tonight.9. He is to leave for Shanghai tomorrow.10. His wish is to become a scientist.11. He managed to finish the work in time.12. Tom came to ask me for advice.13. He found it important to master English.14. Do you have anything else to say?15. To be honest, your pronunciation is not so good.16. Would you please tell me your address?17. He sat there, reading a newspaper.18. _It is our duty to keep our classroom clean and tidy.19. He noticed a man enter the room.20. The apples tasted sweet.一、1、主语,定语;2、间接宾语;3、谓语,状语;4、定语;5、状语,状语;6、定语, 表语;7、宾语,状语;8、谓语,主语;9、谓语;10、主语,表语;11、谓语,宾语;12、 状语;13、形式宾语,真正宾语;14、宾语、定语;15、插入语,状语;16、宾语(间宾+ 直宾);17、状语,状语;18、形式主语、表语,宾补;19、宾补;20、表语二、指出以下句子中划线局部的句子成分:1 .Whether we'll go depend on the weather .2. People's standards of living are going up steadily .3. That was how they wer。defeated.4,The nursery takes good care of our children .5 .ril return the book to you tomorrow .6 .We are sure that we shall succeed .7 .The woman with a baby in her arms is his other sister.8 .There are many films that I'd like to see.9 .Have you met the person about whom he was speaking ?10.1 have a lot of work to do .11. Anyway I won't stop you from doing it.12. She was the first to learn about itHow many new words did you learn last class?13. Seeing his ,some comrades became very worried .14. Much interested , he agreed to give it a try .15. The old man was feeling very tiredWe should serve the people heart and soul.16. You will find it useful after you leave school.17. Spring coming on , the tree turned green.18. Some farmers saw something strange in the skyl.We think it necessary that everyone should attend the meeting .1.1 It's strange that she doesn't come today .1.2 lt was in the library that I found him today .24 .He likes drawing at times when he isn't working .25 .We left in such a hurry that we forgot to lock the door.答案1 .主语从句2谓语3表语从句4宾语5 .间宾6 .宾语从句7.定语8.定语从句9 .定语1。.定语11 .状语12 .定语13 .宾语14 .状语15 .状语16 表语17 .状语 18 .宾补19 .状语20 .定语21 .宾语从句22 .主语从句23 .状语24 .状语25 .状语情况构成方法例词一般情况加-Smap-maps bag-bags car-cars以s. sh, ch. x等结尾的词加-esbus-buseswatch-watchesce. se, ze. (d)ge等结尾的词加-slicense-licenses以辅音字母+y结尾的词变V为i再加es baby-babies名词的格在英语中有些名词可以加“飞”来表示所有关系,带这种词尾的名词形式称为该名词的所有格, 如:a teacher's booko名词所有格的规那么如下:1)单数名词词尾加为”,复数名词词尾没有s,也要加飞”,如the boy's bag男孩的书包,men's room男厕所。2)假设名词已有复数词尾-s ,只加“,如:the workers'struggle工人的斗争。02代词及其基本用法定义:代词是代替名词的词。英语的代词按照其不同的含义与作用可分为9类:人称 代词,物主代词,反身代词,指示代词,相互代词,不定代词,疑问代词,连接代词, 关系代词。1,0人称代词的用法I saw her with them,at least, I thought it was her.我看到她和他们在一起,至少我认为是她。(her 做宾语,them做介词宾语,her作主补)a. - Who broke the vase? 一谁打碎了花瓶?b. - Me.- 0并列人称代词的排列顺序1)单数人称代词并列作主语时,其顺序为:第二人称you第三人称he/she; it第一人称I如: You, he and I should return on time.2)复数人称代词作主语时,其顺序为:第一人称we第二人称you第三人称they如: You, he and I should return on time.反身代词1vouyoushehemyselfyourself .yourselves .herselfhimselfwethey Jitoneowselvesthemselvesitselfoneself指示代词指示代词分单数(this/that)和复数(these/those)两种形式,既可作限定词又可做代词疑问代词指人: who, whom, whose指物:what既可指人又可指物:which03冠词及其基本用法虚词,本身不能独立使用,一般出现在名词前,对名词加以限制。冠词分为不定冠词(a, an) 和定冠词(the)两种。定冠词the表特指,eg the man;不定冠词a(n)在名词前表泛指,eg a man。 定冠词的用法定冠词the与指示代词this,that同源,有“那(这)个”的意思。1)特指双方都明白的人或物:Take the medicine.把药吃了。2)上文提到过的人或事:He bought a house. Tve been to the house.3)指世上独一物二的事物:the sun,the sky,the moon,the earth (敲黑板,这个是经常会在选 择题中考到的知识点)4)单数名词连用表示一类事物,the dollar美元;the fox狐狸;5)用在序数词和形容词最高级,及形容词only,very, same等前面:Where do you live? I live on the second floor.你住在哪?我住在二层。6)与复数名词连用,指整个群体:They are the teachers of this school.指全体教师)They are teachers of this school.(指局部教师)7)用在专有名词前:the People's Republic of China 中华人民共和国The West Lake 西湖8)用在姓氏的复数名词之前,表示一家人:the Greens格林一家人(或格林夫妇)04数词及其基本用法表示数目多少的数词叫基数词;表示顺序的数词叫序数词。序数词表示排列的顺序序数词的缩写形式为阿拉伯数字加序数词的最后两个字母。如:first-1st; second-2nd; third-3rd;基数词变序数词的巧记口诀一二三要全变(one-first; two-second;three- third)其余都加th, th里有例外8 去 t,(eight-eighth) 9 去 e(nine-ninth)字母 f 代 ve (five-fifth; twelve-twelfth);ty 变成 tie (twenty-twentieth)假设要变化几十几,只变个位就可以(twenty-one-twenty-first)数词的用法1)倍数表示法a.主语+谓语+倍数(或分数)+ as + adj. + asI have three times as many as you.我有你三倍那么 多。b.主语+谓语+倍数(分数)+ the size (amount, length.) of.The earth is 49 times the size of the moon.地球是月球的 49 倍。c.主语+谓语+倍数(分数)+形容词(副词)比拟级+ than.The grain output is 8 percent higher this year than that of last year.d.还可以用by+倍数,表示增加多少倍The production of grain has been increased by four times this year.2)分数表示法构成:基数词代表分子,序数词代表分母。分子大于1时,分子的序数词用单数,分母序数 词用复数:1/3 one-third ; 3/37 three and three-sevenths05形容词及其用法定义:形容词用于修饰名词或代词,表示人或事物的性质和特征,在句中可作:定语、表语、 补语或状语。形容词作定语修饰名词时,要放在名词的前边。但是如果形容词修饰以-thing为字尾的词语时,要放在这些词之后,例如:something nice以-ly结尾的形容词l)friendly,deadly,lovely,lonely,likelyjively,ugly,brotherly,仍为形容词。2)有些以-ly结尾既为形容词,也为副词。daily,weekly,monthly,yearly,earlyThe Times is a daily paper. The Times is published daily.用形容词表示类别和整体某些形容词加上定冠词可以泛指一类人,与谓语动词的复数连接。如:the dead,the living,the rich,the poor,the blind,the hungry06副词及其基本用法定义:副词用于修饰动词、形容词、副词、介词短语、句子,主要用作状语,少数与介词同 形的副词还可作表语或补足语。注:副词有9种:时间,地点,方式,程度,疑问,连接,关系,频度和说明性副词。兼 有两种形式的副词1) close 与 closelyclose意思是“近";closely意思是“仔细地”He is sitting close to me. Watch him closely.2)late 与 latelylate意思是“晚”;lately意思是“最近"You have come too late.What have you been doing lately ?形容词与副词的比拟级大多数形容词(性质形容词)和副词有比拟级和最高级的变化,即原级、比拟级和最高级, 用来表示事物的等级差异。原级即形容词的原形,比拟级和最高级有规那么变化和不规那么变化 两种。1)规那么变化2)不规那么变化构成法原级比拟级最局级一般单首T诃未尾加-er, -esttall (高的)tallertallestgreat (巨大的)greatergreatest以不发音的e结尾的单音词 和少数以- le结尾的双音节词 只加工-Stnice (好的)nicernicestlarge(大的)largerlargest以一个辅音字母结尾的闭音节单 音节词,双写结尾的辅音字母, 再加-er, -estbig(大的)biggerbiggesthot (热的)hotterhottest”外辅音字母+y”结尾的双音节词,改 y为 £ 再加 _er, -esteasy (容易的)easiereasiestbusy (忙的)busierbusiest少数以-er, -。火结尾的双音节词 未尾加-eh -estclever (聪明的)cleverercleverestnarrow (窄的)narrowernarrowest其他双音节词和多音节词,在前面 加more, most来构成比拟级和最 高级important (重要的)more importantmost importanteasily(容易地)more easilymost easily有少数形容词、副词的比拟级和最高级是不规那么的,必须熟记。如:good better> bestwell一 better> bestbad> worse> worstill worse一 worstold一 older/elder oldest/eldestmany/much more一 mostlittle> less> leastfar> fiirther/farther furthest/farthest07动词L定义:指表动作的词,还表状态和性质的词,有时态、语态和语气等的变化。2 .功能:放在主语后充当谓语,称为谓语动词,充当其他句子成分时称为非谓语动词,此时 有形式上的变化:doing, to do, done。3 .分类:1)根据在句中的功能,可分为:实意动词(行为动词)系动词助动词情态动词实意动词I live in Beijing with my mother.(我和我妈妈住在北京。)live,住It has a round face.(它有一张圆脸。)has,有系动词系动词本身有词义,但不能单独作谓语,后须跟表语构成系表结构,说明主语的状况、性质、 特征等情况。1)状态系动词:用来表示主语状态,只有be一词,例如:He is a teacher.2)持续系动词:用来表示主语继续或保持一种状况或态度,主要有 keep,rest,remain,stay,lie,stand例如:He always kept silent at meeting.他开会时总保持沉默。3)表像系动词:用来表示“看起来像”这一概念,主要有seem,appear,look 例如:He looks tired.他看起来很累。4)感官系动词:感官系动词主要有feel,smell,sound,taste例如:This kind of cloth feels very soft.This flower smells very sweet.5)变化系动词:这些系动词表示主语变成什么样,变化系动词有 become,grow,turn,fall,get,go,come,run例如:He became mad after that.自那之后,他疯 了。6)终止系动词:表示主语已终止动作,主要有prove,turn out,表达“证实”,“变成”之意例如:The search proved difficult.搜查证实很难。助动词助动词协助主动词构成谓语动词词组的词叫助动词。它本身无词义,不可单独作谓语。基本 动词有:be/do/have。这类词本身无词义,不能单独作谓语,只能与主要动词一起构成谓语,表示不同的时态、语 态、表示句子的否认和疑问,例如:He does not speak English well.(他英语讲得不好。)句中的does是助动词,既表示一般现在时,又与not一起构成否认形式。A dog is running after a cat.(一条狗正在追逐一只猫。)句中的is是助动词,和run的现在分词一起构成现在进行时。Did he have any milk and bread for his breakfast ?(他早餐喝牛奶、吃面包吗?)句中的did是助动词,既表示一般过去时,又和动词have 一起构成疑问。情态动词本身虽有意义,但不完整。它们表示说话人的能力、说话人的语气或情态,如“可能”、“应 当”等。这类动词有can, may, must, need, dare, could, might等。它们不能单独作谓语,必须 与行为动词(原形)一起作谓语,表示完整的意思,例如:I can dance.(我会跳舞。)can,能,会He can9t walk because he is a baby.(因为他是个婴儿,不会走路。)can't,不必May I come in?(我可以进来吗?)may,可以2)根据其后是否可直接跟宾语,可分为及物动词(vt.)不及物动词(vi.),有时同一个动词 既可用作vt.,也可用作vi.。及物动词后面必须跟宾语,意思才完整,例如:Give me some ink, please.(请给我一些墨水。)If you have any questions, you can raise your hands.(如果你们有问题,你们可以举手,。) 不及物动词后面不能跟宾语,意思已完整。不及物动词有时可以加上副词或介词,构成短语 动词,相当于一个及物动词。例如:He works hard.(他工作努力。)Jack runs faster than Mike.(杰克跑步比迈克要快些。)Please look at the blackboard and listen to me.(请看黑板,听我说。)He got and “A" this time because he went over his lessons carefully.(这次他得了 个“A",因为他 仔细地复习了功课。)注:l)vt.不可单独使用,必须和其后的宾语一起使用,有被动语态。vi.后不能直接跟宾语, 假设跟宾语,必须借助于介词或其他词类;也可单独使用,无被动。3)从是否延续来分,可分为延续性动词非延续性动词(短暂性动词)延续性动词表示可以持续的动作或者状态,也称为持续性动词。常见的延续性动词有:have,drink, eat, sleep, work, stand, walk, snow, wait, keep, lie, read, play, live, sing, run, smoke, study, wear.It has been raining for three days.已经下了三天的雨了。Everyone can at least keep the book for 10 days.这本书大家起码可以借十天。非延续性动词表示短暂、瞬间完成的动作,也称为短暂性动词或终止性

    注意事项

    本文(第03讲-词性和句子成分 2022年初高中英语无缝衔接讲义20讲+精练(解析版)公开课.docx)为本站会员(太**)主动上传,淘文阁 - 分享文档赚钱的网站仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知淘文阁 - 分享文档赚钱的网站(点击联系客服),我们立即给予删除!

    温馨提示:如果因为网速或其他原因下载失败请重新下载,重复下载不扣分。




    关于淘文阁 - 版权申诉 - 用户使用规则 - 积分规则 - 联系我们

    本站为文档C TO C交易模式,本站只提供存储空间、用户上传的文档直接被用户下载,本站只是中间服务平台,本站所有文档下载所得的收益归上传人(含作者)所有。本站仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私,请立即通知淘文阁网,我们立即给予删除!客服QQ:136780468 微信:18945177775 电话:18904686070

    工信部备案号:黑ICP备15003705号 © 2020-2023 www.taowenge.com 淘文阁 

    收起
    展开