-
人教版高中英语必修3Festivals around the World说课稿3篇
Teaching plan for Unit 1 book3Good morning, teachers. It’s my great pleasure to be here because I can share my lesson with you and I can learn a lot from it. I’ll begin my lesson from the following four parts， the teaching material, the teaching methods, the studying methods and the teaching procedure.Firstly, let me talk about the teaching material. The content of my lesson is the reading passage festivals and celebrations of Unit 1 Festivals around the world. This passage is about festivals and celebrations. By studying this passage, we’ll enable the students to know that festivals exit everywhere, and many of festivals in different countries celebrate similar ideas. As we all know, the reading passage is the center of each unit. If the Ss can learn it well, it will be helpful to make the Ss learn the rest of this unit.After studying the teaching material, I think the teaching aims are as the followings:1. Knowledge aims:(1) The Ss can master the usage of the important words andexpressions.(2)The Ss can use the __________________ (grammar) in the proper situation.Make students know about the festivals all over the world and the detail of the festivals, such as origin, content, and the date of the holiday festivals.2. Ability aims:(1) Students can talk about festivals and celebrations in English(2) To improve the student’s reading ability, especially their skimming and scanning ability.3. Emotion aims:Make the Ss know about the foreign festivals, and respect other countries’ custom.Next, let’s come to the important points and the difficult points.The important point is how to make the Ss understand the text better and the difficult point is how can they talk about it. secondly， Teaching Methods:1. task-based Language Teaching2. Computer assisted language teaching.3. question-and–answer methodThirdly， Studying Methods:
人教版高中英语必修4Theme parks说课稿3篇
The oldest and the most popular park in the worldenjoy the exciting activities thereget close to the life-size cartoon characters like Mickey Mouse and Donald Duck Step 3 Pre-reading1.What do you suppose a theme park is ?2.What do you think you can see in a theme park?(1.It is a kind of amusement park which has a certain theme – that the whole park is based on. 2.buildings, castles, statues, rare animals and birds, and so on.) Step 4 Reading ----- Theme Parks –---- Fun and More Than Fun1.Predict : Read the title and the pictures on P. 34 and PredictWhat is the meaning of the title “Theme Park – Fun and more than fun”?(The title means that theme parks are fun to visit, but that they can also be educational and can offer useful information.)2.Skimming Fast read and answer:What activities can we take in a theme park?Amusement park: Bumper car Merry-go-round slide bungee jumping Free-fall rides Horror films Pirate ship Ferris wheel roller coaster3.Scanning Read again and you will find various theme parks are mentioned in the passage . Then what are they ?Theme parks: Sports theme park History theme park Culture theme park Marine or Ocean theme Park Future park Science theme park Disneyland4.Careful reading and find the main idea of each paragraph:THEME PARKS---- entertaining/ educationalPara.1 Traditional parks are places to go for relaxation and to have time away from our busy lives.Para.2 Theme parks are different They’re large and full of things to do, see and buy.Para.3 Theme parks are built around a single idea or theme. One example is a sports park.Para.4 Another kind of theme park is historical more and cultural and can be educational.Para.5 Disneylandwas the first theme park. It is based on the fantasy life and characters of Disney’s films.Para.6 Some examples of educational theme parks include sea world parks and science parks.
人教版高中英语必修3Healthy Eating说课稿4篇
Language learning needs a context, which can help the learners to understand the language and then can product comprehensible output, so computer has the advantages to make the materials attractive.Part 3 Learning MethodsTask-based, self-dependent and cooperative learningPart 4 Teaching ProcedureStep One Lead-in“Interest is the best teacher.” Therefore, at the very beginning of the class, I should spark the students’ mind to focus on the centre topic “the band”. I’ll show some pictures of food to attract their attention and then bring some questions.Question:What kind of food they like?What should go into a good meal?The answers must relate to the diet. After this, the students will be eager to know something about a balance diet and this is the very time to naturally lead the class into Step 2Step 2 Reading for information: skimming and scanning In this step, I use Task-based Language Teaching method, which can give students a clear and specific purpose while skimming and scanning the context.Task 1 General ideaThe students will be asked to just glance at the title and the pictures of the passage, and then guess what they will read in the text. And they’ll be divided into groups of four to have a discussion.The purpose is to inspire the students to read actively, not passively. In addition, the task is to develop the students’ reading skill by making prediction and to encourage the students to express their thoughts in English and cooperate with each other.Task 2 Main idea of each paragraphCooperative learning can raise the students’ interest and create an atmosphere of achievement. Based on this theory, I divide the whole class into 4 groups to skim the whole text and get the main idea of each paragraph.
人教版高中英语必修4Working The Land说课稿3篇
Knowledge objectives:(1) to make Ss grasp the usage of words, expressions and sentence structures: statistics, struggle, thanks to, rid of, some patterns for persuasion, the “ing” form as subject and object;(2)to use learnt knowledge to persuade sb.Ability objectives:(1) to develop Ss’ reading skills(skimming, scanning, word guessing);(2) to improve Ss’ speaking, communicating and cooperating skills.Emotional objectives:to make Ss know the contribution of Yuan,and learn his spirit and his simple life time.Teaching important and difficult points:(1) some words, expressions and sentence structures mentioned above;(2)the content of the text;(3)training their reading and speaking skills.Teaching methods: CLT, TBLT,QT.Learning strategies: CLS, QLS, TBLS.Teaching procedures:Step 1 lead-in: (1) teacher plays a piece of recent news from CCTV about the harvest of the super hybrid rice, and ask students whether they know Yuan or not, and talk about him and his contribution.(2)Brain storm: let Ss describe Yuan in their minds including his appearance, his living condition and so on.Step 2 fast reading tasks:(1)teacher introduces Yuan and super hybrid rice(2)make Ss read the text as fast as possible with questions. Such as: what’s the general ideaof this passage? What’s Yuan’ dream? (skimming and scanning skill)Step 3 intensive reading tasks(1)let Ss read the text silently, find topic sentence of each paragraph and draw the difficult sentences and the knowledge what they don’t understand.(words guessing)(2)teacher and Ss talk about the important words, expressions and sentences together, and ask Ss to retell the content of the text.(summarizing and paraphrasing)(3)teacher summarize this part.(4) read again following the courseware.
人教版高中英语必修3The million pound bank note说课稿3篇
在接下来的细读环节，我套用了高考对阅读理解的考查方式设置了5个问题，分别为三个推理判断题，一个细节题和一个主旨大意题。学生需要对文章的内容进行分析、归纳、推理、猜测等高级思维活动才能做出正确的回答。【设计意图】这一过程是对学生进行细读的训练，培养学生获取特定信息和挖掘文章深层次信息的能力。第三环节:Intensive-reading (精读) 15′第三个环节精读，既是最重要的环节，也是突破本课重难点的关键。首先，让学生思考剧本中人物看到百万英镑前后的态度发生了怎样的变化。其次，让学生仔细阅读文章，找出可以表现人物态度变化的具体的语言和动作。最后，让学生总结人物的态度发生变化的根本原因是什么，从而引出Money Talks, 供学生思考。【设计意图】通过一系列的活动培养学生学习从人物的语言和动作探究人物的心理，使学生进一步体会戏剧语言的魅力，从而对文章背后所反映的社会问题进行思考，也为下一步的讨论环节做好铺垫。
人教版高中英语必修5First aid说课稿6篇
In this class, I have 3 teaching aims, that is, knowledge aims, ability aims and emotion aims.1) Knowledge-Teach students new words and expressions, such as temporary, bleed,sprain choke, first aid, fall ill and so on.-Enable students to have a better understanding for some basic knowledge of first aid.2) Ability-Train students’ speaking, reading and writing abilities by different teaching activities, such as skimming, comprehending, team work, role play, retelling and writing.-Develop students’ reading strategy on how to move general idea to specific information.3) Emotion-Promote students’ awareness of giving first aid.- Cultivate students’ creativities.Then let’s come to my teaching methods and activities.III. Teaching methods and activities:To achieve different teaching aims, various kinds of teaching methods and activities will be adopted throughout this period, such as TBL (task-based learning), skimming, team work, brainstorm and others, which can offer students opportunities to fulfill tasks in which they can use language to achieve a specific outcome.IV. Teaching aids:Computer and blackboardV. Teaching important points:1) Make students have a clear mind for the structure of the text.2) Help students understand the theme of the text.VI. Teaching difficulties:1) So many new words may affect students’ understanding.2) How to get students to know about the functions of the skin and thecauses, characteristics and treatments for different degree burns,and the knowledge about giving first aid. VII. Blackboard design:
人教版高中英语必修5Great scientists说课稿4篇
通过写文章梗概，培养学生综合运用语言的能力，学习用恰当的英语描述科学家的故事。这是本课的教学难点。教师可以使用完形填空的方式来帮助学生整理语篇，从而来降低难度。本课的教学重点的突破方法是：在阅读前，让学生初步了解得出科学观点所需要的基本程序，从而轻松而自然地导入文章的阅读；在阅读过程中，由易到难设计快速阅读和精读的问题，层层推进各种阅读活动，让学生对阅读内容从整体感知到细节理解，最后深层读懂整篇文章，同时加强阅读策略的指导，让每个学生都主动参与课堂教学活动，最终达到提高阅读能力的目的。Step 4 Post-readingGroup Activities四人小组共同合作，在老师的适当指导下，就以下2个问题展开讨论，让学生就所知、所学、所感和所想融入话题，然后抽若干同学代表作小组发言。1. What do you think about John Snow, and what should we learn from him?2. Cholera was 19th century disease, which two diseases are similar to cholera today? Why?
人教版高中英语必修5Life in the Future说课稿5篇
Good afternoon, everyone. It’s my great pleasure to be here sharing my lesson with you. The content of my lesson is Senior English for China Book5 Unit 3 Life in the Future. I’ll be ready to begin this lesson from six parts: Analysis of the teaching material, Analysis of the students, Teaching aims and important and difficult points, Teaching methods and aids, Teaching procedures, and Blackboard design. First, let me talk about the teaching material.Part 1 Analysis of the Teaching Material:This unit is about what human beings’ life will be like in about one thousand years. By studying of this unit, we’ll Enable the students to know the changes in humans’ life and some new inventions bringing about the change and develop the interest in science. This lesson plays an important part in the English teaching in this unit. This is an important lesson in Book Five. From this lesson, it starts asking the Ss to grasp contents of each passage. Therefore, this lesson is in the important position of the teaching material. If the Ss can learn it well, it will be helpful to make the Ss learn the rest of this unit.Part 2 Analysis of the SsAs Senior2 Ss, they are at different levels of English fluency, some of them have lost interest in English. So during the lesson, I arrange a variety of activities to let all of them join in to attract their interest and let them be confident and taste the joy of success.
人教版高中英语必修5Making the news说课稿4篇
今天我们来介绍一下必修五第四单元的授课方式。这个单元的题目是Making the news。应该是学生比较感兴趣的话题，学生往往对新闻工作充满好奇，所以我们可以利用这个机会多设计一些师生互动和学生互动，来激发起学习的积极性，提高学习效率。同时我们可以利用这个单元不仅帮助学生掌握语言知识，培养语言能力，同时让其了解新闻工作的重要性，培养起社会智能感。这个单元分为六个课时，它的教学目标是这样的：语言目标是掌握词汇表中的常用单词和短语，掌握倒装句的一些基本用法。 技能目标是能初步掌握约会的基本句型并在真实的场景下正确运用。新闻报道类文章的写作技能。采访的基本规范和沟通技能。情感目标是对新闻报道的客观性和真实性有更好的理解。对新闻记者的职业有更深入的了解，并能体会其工作的重要性。下面我们来介绍一下第一课时的授课方式，第一课的教学目标是这样的第一课时的教学目标语言目标:单词：Occupation, journalist, editor, photographer, curious, personality, enthusiasm
人教版高中英语必修5The United Kingdom说课稿4篇
Teaching Aims:Knowledge 1. Get the students to learn the useful new words and expressions in this section. Aims:2. Let the students learn about how the UK was formed and the four groups of invaders.1. Develop students’ reading ability and let them learn different Ability reading skills. Aims:2. Enable students to learn to talk about the United Kingdom and the Union Jack Emotional 1. Let students know more about the UK2. Develop students’ sense of cooperative learning Aims:Teaching Important Points:1. Let the students learn about the countries of the United Kingdom and the Union Jack2. Get the students to read the passage and know about how the UK was formed and the four groups of invaders.3. Have the students learn different reading skills.Teaching Difficult Ponts:1. Develop students’ reading ability.2. Enable students to talk about the United Kingdom and the Union Jack.3. Let students learn how the UK was formed geographically and historically.Teaching Methods:Showing pictures, asking, exercising, listening, reading etc.Teaching Aids:A computer,a projector and a blackboard.Teaching Procedures: 1) Show a map of the world, ask students the following questions:Where is the UK?What’s the full name of the UK?2) Ask the students work in pairs to do the quiz on Page 9.Do you want to test how many things you know about the United Kingdom? Let’s have a small test.Using the map on P9, students answer the following questions:?How many countries does the UK consist of? What are they??England is divided into three main areas. Do you know what they are? 1) Scanning (10Minutes )Let the students hold the questions asked in pre-reading and read the passagequickly and then let them do the following exercise.Join lines to the right answer.
人教版高中语文必修3《过秦论》说课稿3篇
本文篇幅较长，并且有一字句不易理解，因而对高一学生来说完全读懂内容有一些困难。这样的话，老师就要做好引导工作，把一些难点，或是出现词类活用比较多，局势比较特殊的句子，老师可以先给学生画出来，存疑，或是与同学们一起讨论解决。对那些不易懂的字词就引导学生联系上下文提供的语境、前后涉及的情节加以推测、判断，以培养学生依据文脉推断词义的好方法。要求学生点出重点实词、框出通假字，主要是为帮助学生积累和掌握一些文言文中常见的一词多义、异读现象、古今异义和通假现象的词语，并进一步得出规律，指导今后的文言文学习。词类活用和特殊句式在文言文翻译中难度较大，也是本文教学的两大难点。要求学生标出有活用现象的字和划出句式特殊的句子，是基于两点考虑：1、积累一定数量的第一手例句；2、引导学生加以分类，找出每类的相同特征，并抽取出来形成规律性的东西，从而上升到理性认识，使学生能由学会一个到会学多个。翻译过程中注重指导学生养成用符号法表示重点字句的好习惯，如点、框、圈、划线等符号应约定一致，便于突出翻译中的重点、难点及复习。我的提示着重归纳了实词“制”“亡”“遗”“利”等，名词活用、形容词活用、使动用法，被动句、状语后置句。
人教版高中语文必修3《爱的奉献 学习议论中的记叙》说课稿
教学过程：（一）导入：课前放《爱的奉献》歌曲，同时不断播放一些有关“爱”的主题的图片，渲染一种情感氛围。师说：同学们，谁能说说这组图片的主题应该是什么？生（七嘴八舌）：母爱，不对是亲情……是友情、还有人与人互相帮助……那组军人图片是说保卫国家，应该是爱国……那徐本禹和感动中国呢？…………生答：是关于爱的方面师说：不错，是关于爱的方面。那么同学们，今天就以“爱的奉献”为话题，来写一篇议论文如何？生答：老师，还是写记叙文吧。生答：就是，要不议论文写出来也象记叙文。师问：为什么？生答：老师，这个话题太有话说了，一举例子就收不住了，怎么看怎么象记叙文。生答：就是，再用一点形容词，就更象了。众人乐。师说：那么同学们谁能告诉我，为什么会出现这种问题？一生小声说：还不是我们笨，不会写。师说：不是笨，也不是不会写，你们想为什么记叙文就会写，一到议论文就不会了，那是因为同学们没有明白议论文中的记叙与记叙文中的记叙有什么不同，所以一写起议论文中的记叙，还是按照记叙文的写法写作，这自然就不行了。那好，今天我们就从如何写议论文中的记叙讲起。
人教版高中政治必修4时代的精神的精华说课稿
（二）能力目标培养学生运用哲学理论观察、分析、处理社会问题的能力，增强学生的时代感。（三）情感、态度与价值观目标培养学生与时俱进的思想品质，让学生关注时代、关注现实、关注生活，逐步树立科学的世界观、人生观、价值观。三、说教学重难点：时代精神的总结和升华是本框的难点，虽然学生在文化生活中学习了文化与经济政治的关系，但要让学生得出哲学是时代精神的总结和升华，还要联系前面关于哲学的基础知识进行总结归纳，因此可能会难以把握，另外关于什么样的哲学是真正的哲学的理解会稍有难度。社会变革的先导是本框的重点，一方面哲学源于时代，另一方面强调哲学反过来对时代又有重要的反作用，突出这一点能够更好地激发学生学习哲学的热情和信心，对于后面知识的学习是极为有益的，因此社会变革的先导这一目作重点处理。
人教版高中历史必修3现代中国教育的发展说课稿
一、教材分析下面我来谈一谈对教材的认识：主要从教材的地位和作用、以及在此基础上确立的教学目标、教学重难点这三个方面来谈。首先，来谈教材的地位和作用：本课教材内容主要从三个方面向学生介绍了现代中国教育的发展状况和趋势：人民教育的奠基、动乱中的教育和教育的复兴，全面讲述了新中国教育的三个阶段。本课是文化史中中国史部分的最后一课， 也是必修三册书中唯一涉及教育的一课。而教育是思想文化史中的重要组成部分，江泽民同志在谈到教育的时候曾经说过，“百年大计，教育为本。教育为本，在于育人”。教育是关系国计民生的大事。学生通过学习新中国教育发展的史实，理解“科教兴国”、“国运兴衰，系于教育”的深刻含义。最终由此激发学生树立“知识改变命运、读书成就人生”的信念，树立勤奋学习、成人成才、报效祖国、服务社会的崇高理想。故本课的教学有极大的现实意义。谈完了教材的地位和作用，我再分析一下教学目标：
人教版高中数学选择性必修二导数的四则运算法则教学设计
求函数的导数的策略(1)先区分函数的运算特点，即函数的和、差、积、商，再根据导数的运算法则求导数；(2)对于三个以上函数的积、商的导数，依次转化为“两个”函数的积、商的导数计算．跟踪训练1 求下列函数的导数：(1)y＝x2＋log3x； (2)y＝x3·ex； (3)y＝cos xx.[解] (1)y′＝(x2＋log3x)′＝(x2)′＋(log3x)′＝2x＋1xln 3.(2)y′＝(x3·ex)′＝(x3)′·ex＋x3·(ex)′＝3x2·ex＋x3·ex＝ex(x3＋3x2)．(3)y′＝cos xx′＝?cos x?′·x－cos x·?x?′x2＝－x·sin x－cos xx2＝－xsin x＋cos xx2.跟踪训练2 求下列函数的导数（1）y＝tan x； （2）y＝2sin x2cos x2解析：（1）y＝tan x＝sin xcos x，故y′＝?sin x?′cos x－?cos x?′sin x?cos x?2＝cos2x＋sin2xcos2x＝1cos2x.（2）y＝2sin x2cos x2＝sin x，故y′＝cos x.例5 日常生活中的饮用水通常是经过净化的，随着水的纯净度的提高，所需进化费用不断增加，已知将1t水进化到纯净度为x%所需费用（单位：元），为c(x)=5284/(100-x) (80<x<100)求进化到下列纯净度时，所需进化费用的瞬时变化率：（1） 90% ；（2） 98%解：净化费用的瞬时变化率就是净化费用函数的导数；c^' (x)=〖(5284/(100-x))〗^'=(5284^’×(100-x)-"5284 " 〖(100-x)〗^’)/〖(100-x)〗^2 =(0×(100-x)-"5284 " ×(-1))/〖(100-x)〗^2 ="5284 " /〖(100-x)〗^2
人教版高中数学选择性必修二导数的概念及其几何意义教学设计
新知探究前面我们研究了两类变化率问题：一类是物理学中的问题，涉及平均速度和瞬时速度；另一类是几何学中的问题，涉及割线斜率和切线斜率。这两类问题来自不同的学科领域，但在解决问题时，都采用了由“平均变化率”逼近“瞬时变化率”的思想方法；问题的答案也是一样的表示形式。下面我们用上述思想方法研究更一般的问题。探究1： 对于函数y=f(x) ，设自变量x从x_0变化到x_0+ ?x ，相应地，函数值y就从f(x_0)变化到f(〖x+x〗_0) 。这时， x的变化量为?x，y的变化量为?y=f(x_0+?x)-f(x_0)我们把比值?y/?x，即?y/?x=(f(x_0+?x)-f(x_0)" " )/?x叫做函数从x_0到x_0+?x的平均变化率。1．导数的概念如果当Δx→0时，平均变化率ΔyΔx无限趋近于一个确定的值，即ΔyΔx有极限，则称y＝f (x)在x＝x0处____，并把这个________叫做y＝f (x)在x＝x0处的导数(也称为__________)，记作f ′(x0)或________，即
人教版高中数学选择性必修二等比数列的概念 (2) 教学设计
二、典例解析例4. 用 10 000元购买某个理财产品一年.（1）若以月利率0.400%的复利计息，12个月能获得多少利息（精确到1元）？（2）若以季度复利计息，存4个季度，则当每季度利率为多少时，按季结算的利息不少于按月结算的利息（精确到10^(-5)）？分析：复利是指把前一期的利息与本金之和算作本金，再计算下一期的利息.所以若原始本金为a元，每期的利率为r ，则从第一期开始，各期的本利和a , a(1+r)，a(1+r)^2…构成等比数列.解：（1）设这笔钱存 n 个月以后的本利和组成一个数列{a_n }，则{a_n }是等比数列，首项a_1=10^4 (1+0.400%)，公比 q=1+0.400%，所以a_12=a_1 q^11 〖=10〗^4 (1+0.400%)^12≈10 490.7.所以，12个月后的利息为10 490.7-10^4≈491（元）.解：（2）设季度利率为 r ，这笔钱存 n 个季度以后的本利和组成一个数列{b_n }，则{b_n }也是一个等比数列，首项 b_1=10^4 (1+r)，公比为1+r，于是 b_4=10^4 (1+r)^4.
人教版高中数学选择性必修二等差数列的概念（2）教学设计
二、典例解析例3.某公司购置了一台价值为220万元的设备，随着设备在使用过程中老化，其价值会逐年减少.经验表明，每经过一年其价值会减少d(d为正常数）万元.已知这台设备的使用年限为10年，超过10年 ，它的价值将低于购进价值的5%，设备将报废.请确定d的范围.分析：该设备使用n年后的价值构成数列{an}，由题意可知，an＝an－1－d (n≥2). 即：an－an－1＝－d.所以{an}为公差为－d的等差数列.10年之内（含10年），该设备的价值不小于（220×5%=）11万元；10年后，该设备的价值需小于11万元．利用{an}的通项公式列不等式求解．解：设使用n年后，这台设备的价值为an万元，则可得数列{an}．由已知条件，得an＝an－1－d（n≥2）．所以数列{an}是一个公差为－d的等差数列.因为a1＝220－d，所以an＝220－d＋(n－1)(－d)＝220－nd. 由题意，得a10≥11，a11＜11. 即：{█("220－10d≥11" @"220－11d＜11" )┤解得19<d≤20.9所以，d的求值范围为19<d≤20.9
人教版高中数学选择性必修二等比数列的前n项和公式 (2) 教学设计
二、典例解析例10. 如图，正方形ABCD 的边长为5cm ，取正方形ABCD 各边的中点E,F,G,H, 作第2个正方形 EFGH，然后再取正方形EFGH各边的中点I,J,K,L，作第3个正方形IJKL ，依此方法一直继续下去. (1) 求从正方形ABCD 开始，连续10个正方形的面积之和；(2) 如果这个作图过程可以一直继续下去，那么所有这些正方形的面积之和将趋近于多少？分析：可以利用数列表示各正方形的面积，根据条件可知，这是一个等比数列。解：设正方形的面积为a_1，后续各正方形的面积依次为a_2, a_(3, ) 〖…,a〗_n,…，则a_1=25,由于第k+1个正方形的顶点分别是第k个正方形各边的中点，所以a_(k+1)=〖1/2 a〗_k,因此{a_n}，是以25为首项，1/2为公比的等比数列.设{a_n}的前项和为S_n（1）S_10=(25×[1-(1/2)^10 ] )/("1 " -1/2)=50×[1-(1/2)^10 ]=25575/512所以，前10个正方形的面积之和为25575/512cm^2.(2)当无限增大时，无限趋近于所有正方形的面积和
人教版高中数学选择性必修二等差数列的前n项和公式（2）教学设计
课前小测1．思考辨析(1)若Sn为等差数列{an}的前n项和，则数列Snn也是等差数列．( )(2)若a1>0，d<0，则等差数列中所有正项之和最大．( )(3)在等差数列中，Sn是其前n项和，则有S2n－1＝(2n－1)an.( )[答案] (1)√ (2)√ (3)√2．在项数为2n＋1的等差数列中，所有奇数项的和为165，所有偶数项的和为150，则n等于( )A．9 B．10 C．11 D．12B [∵S奇S偶＝n＋1n，∴165150＝n＋1n.∴n＝10.故选B项．]3．等差数列{an}中，S2＝4，S4＝9，则S6＝________.15 [由S2，S4－S2，S6－S4成等差数列得2(S4－S2)＝S2＋(S6－S4)解得S6＝15.]4．已知数列{an}的通项公式是an＝2n－48，则Sn取得最小值时，n为________.23或24 [由an≤0即2n－48≤0得n≤24.∴所有负项的和最小，即n＝23或24.]二、典例解析例8.某校新建一个报告厅，要求容纳800个座位，报告厅共有20排座位，从第2排起后一排都比前一排多两个座位. 问第1排应安排多少个座位？分析：将第1排到第20排的座位数依次排成一列，构成数列{an} ，设数列{an} 的前n项和为S_n。