提供各类精美PPT模板下载
当前位置:首页 > Word文档 >

北师大初中数学九年级上册比例的性质1教案

  • 新人教版高中英语选修1Unit 4 Body Language教案

    新人教版高中英语选修1Unit 4 Body Language教案

    本阅读材料的话题是交际中的肢体语言,作者从三个方面讲述了肢体语言的特征与作用,通过主题句和举例阐述的方式让读者了解不同文化中肢体语言的相同或者不同的意义,并从更抽象、概括的维度深入认识肢体语言的特点,理解肢体语言的作用。基于肢体语言的特点,作者提醒读者在与人交流中,尤其是当文化背景有差异的时候,要使用得体的肢体语言,尊重、理解和包容不同的文化,进行有效、有素养的沟通。文本共由六个段落组成,篇章结构为“总—分”。第一段用简练的语言引出了话题,并且从我们自身表达的需要和了解他人感受两个角度讲述了肢体语言的作用。第二段阐述了肢体语言的第一个重要特点——肢体语言在不同的文化中有不同的内涵——这也是文中写作篇幅最大的一个要点,最为重要。通过讲述肢体语言的这一特点,作者向读者传递了要尊重不同的文化、要使用与所在文化相宜的肢体语言。

  • 新人教版高中英语选修4Unit 1 Science Fiction教案

    新人教版高中英语选修4Unit 1 Science Fiction教案

    本活动旨在落实课时教学目标2。 1.Think, discuss and share. Students form groups of 4, discuss about the given ending make comments. Q1: Do you like the ending? Q2: Was it a logical ending? Why so or why not? [设计意图]通过引导学生思考、讨论、评价,比较个人、同伴所预测的结局和听力文本所给定的结局的异同点,深化对文本的认知,发展学生的评判性思维能力。 Activity 4: Exploring Asimov’s three laws of robotics and the purpose of the writing 本活动旨在落实课时教学目标3。 1. Get to know Isaac Asimov’s three laws of robotics. The teacher shares Isaac Asimov’s three laws of robotics. The three laws state that: ①A robot may not injure a human being or, through inaction, allow a human being to come to harm. ②A robot must obey any orders given to it by human beings, except where such orders would conflict with the First Law. ③A robot must protect its own existence as long as such protection does not conflict with the First or Second Law. Q: How does Tony’s story relate to the laws? 2. Figure out Isaac Asimov’s purpose of writing Satisfaction Guaranteed. The students express their opinions about the author’s writing purpose. Q: Why did Isaac Asimov write such a story? S: To explore the relationship between robots and humans. [设计意图]通过了解艾萨克·阿西莫夫所制定的机器人三大定律,加深学生对文本的理解,深入探究文本的主题意义。推理作者的写作目的,联系生活实际,思考人类与机器人的关系。

  • 新人教版高中英语选修3Unit 1 Art教案

    新人教版高中英语选修3Unit 1 Art教案

    [2] An important breakthrough…was… [3] Another innovation was … [4] the emphasis increasingly shifted from…to… [5] New ideas and values gradually replaced… [6] While his paintings still had religious themes… … T: All these expressions serve to show how Western painting has developed. Some of them share similar structure but with varied use of words, which makes the text vivid and more readable. 【设计意图】主题类语言整理有助于学生类化语言应用,提高语言输出的丰富性。处理完文本内容信息后,进入语篇信息处理,进行主题相关的词块归类。引导学生快速阅读,寻找表达相同主题(发展或者艺术)的词和短语,再根据词性、用法和结构进行归类,储备主题相关词汇,丰富语言储备,提升语言素养。 Assignment: Go online to gather more information about Chinese painting and write a short history of it. 【设计意图】结合所学,迁移运用,根据实际语境,进行模仿性运用。在此过程中,学生尝试借鉴已学的语言、内容、语篇结构和写作手法来建构新文本,实现语篇输出,同时关注中西艺术文化的差别,加深对优秀文化的认同,培养文化意识。

  • 人教版高中地理必修1常见天气系统教案

    人教版高中地理必修1常见天气系统教案

    知识和技能 ⑴从图片和简易图中,了解气团(冷气团、暖气团)的概念;锋的概念与分类;低压(气旋)、高压(反气旋)、高压脊、低压槽的概念。⑵从气温、气压、湿度、降水、风等几方面分析各种天气系统的形成及其气流特点,并综合出各种天气系统控制下的天气状况过程与方法 ⑴让学生能阅读和简单分析天气图,解释天气变化现象;⑵用案例说明气象灾害发生的原因和危害;⑶结合我国常见的天气系统说明其对人们生产和生活的影响情感、态度与价值观激发学生探究天气的形成和变化的兴趣和动机,培养学生求真、求实的科学态度,提高地理审美情趣教学重点1.锋面系统。(锋面系统:一是要区别冷暖锋的成因,二是要掌握锋面两侧的气压、温度、湿度、风和天气差异)2.低压、高压系统。(要掌握其成因、气压特征、气流特征及其天气特点四个方面。)

  • 人教版高中地理选修1月球和地月系教案

    人教版高中地理选修1月球和地月系教案

    月球对地球的意义月球与地球形影相随,关系密切。月球对地球的影响,主要有以下几方面:1.地球上夜晚的自然照明,主要靠月亮。2.远在古代,人们就根据月相变化的周期,编订历法。我国农历月份的安排,是以月相变化 周期为标准的。农历规定朔为初一,这样,望就在十五日或十六日。我国人民的传统节日,像春节、中秋节就是按农历的月日计算安排的。3.由于地球表面各处所受月球和太阳引力的不同,地球上的水体产生了明显的潮汐现象。4.月球是人类星际航行的第一站。已知月球表面有多种宝贵矿藏;重力较小;没有大气层,利用太阳能的条件较好。如何利用月球的特殊环境,开发月球的资源,以及如 何利用月球作“码头”,使人类更好地研究宇宙,这将是月地关系的新篇章。

  • 人教版高中地理选修1月相和潮汐变化教案

    人教版高中地理选修1月相和潮汐变化教案

    5.对土星五号火箭和登月舱的质疑现代航天飞机只能把20吨载荷送上低轨,而当 年的土星五号却能轻而易举地把100吨以上载荷送上地球轨道,将几十吨物体推出地球重力圈,为什么后来却弃而不用,据说连图纸都没有保存下来?6.温度对摄影器材的影响月面白天可达到121°C,据图片看,相机是露在宇航服外而没有采用保温措施的。胶卷在66°C就会受热卷曲失效,怎么拍得了照片?这些人士认为,对以上这一切美国政府一直没个 交代,而知情者由于担心生活和安全受到影响,甚至可能直接遭到了胁迫,至今对此沉默不言。但相信不久的将来,诞生于美苏太空竞赛年代的“登月骗局”定会水落石出。反驳不过,也有许多人认为“阿波罗”登月计划不可能造假:首先因为该计划当时是在全球实况转播的,近亿人亲眼看到。另外,宇航员还从月球带回了一些实物,如岩石。

  • 人教版高中地理选修1太阳和太阳系教案

    人教版高中地理选修1太阳和太阳系教案

    彗星简介:(1)云雾状的独特外貌,质量很小;(2)主要由冰物质构成(含尘埃、水、甲烷、二氧化碳等),有人称它为“脏雪球”;(3)结构分彗核、彗发、彗尾(分离子尾、尘埃尾),彗星在远离太阳时,只有一个冰冻的彗核,当行进太阳时,组成物质升华而形成彗发,在太阳风的吹拂下,背向太阳的一侧出现彗尾,远离太阳时,彗尾消失,尾永远背向太阳;(4)目前已经 发现了1600多颗彗星,最著名的就是哈雷彗星,1985~1986 年,曾回归;(5)彗星的公转周期各不相同,相差极大,有的几十年,有的几百年,哈雷彗星的公转周期为76年。学生讨论回答,然后速读课文“流星体”。【启发引导】行星际空间是否是“真空”状态?行星际空间分布着极其稀薄的气体和尘埃,称为行星际物质,行星际物质的来源——太阳风、星际冲撞……

  • 人教版新课标高中物理必修1弹力教案2篇

    人教版新课标高中物理必修1弹力教案2篇

    一般情况下,凡是支持物对物体的支持力,都是支持物因发生形变而对物体产生弹力。所以支持力的方向总是垂直于支持面而指向被支持的物体。例1:放在水平桌面上的书书由于重力的作用而压迫桌面,使书和桌面同时发生微小形变,要恢复原状,对桌面产生垂直于桌面向下的弹力f1,这就是书对桌面的压力;桌面由于发生微小的形变,对书产生垂直于书面向上的弹力f2,这就是桌面对书的支持力。学生分析:静止地放在倾斜木板上的书,书对木板的压力和木板对书的支持力。并画出力的示意图。结论:压力、支持力都是弹力。压力的方向总是垂直于支持面而指向被压的物体,支持力的方向总是垂直于支持面而指向被支持的物体。引导学生分析静止时,悬绳对重物的拉力及方向。引导得出:悬挂物由于重力的作用而拉紧悬绳,使重物、悬绳同时发生微小的形变。重物由于发生微小的形变,对悬绳产生竖直向下的弹力f1,这是物对绳的拉力;悬绳由于发生微小形变,对物产生竖直向上的弹力f2,这就是绳对物体的拉力。

  • 人教版新课标高中物理必修1摩擦力教案2篇

    人教版新课标高中物理必修1摩擦力教案2篇

    l.知识与技能:(1)知道摩擦力产生的条件。(2)能在简单问题中,根据物体的运动状态,判断静摩擦力的有无、大小和方向;知道存在着最大静摩擦力。(3)掌握动磨擦因数,会在具体问题中计算滑动磨擦力,掌握判定摩擦力方向的方法。(4)知道影响到摩擦因数的因素。2.过程与方法:通过观察演示实验,概括出摩擦力产生的条件及摩擦力的特点,培养学生的观察、概括能力。通过静摩擦力与滑动摩擦力的区别对比,培养学生分析综合能力。3.情感态度价值观:在分析物体所受摩擦力时,突出主要矛盾,忽略次要因素及无关因素,总结出摩擦力产生的条件和规律。二、重点、难点分析1.本节课的内容分滑动摩擦力和静摩擦力两部分。重点是摩擦力产生的条件、特性和规律,通过演示实验得出关系f=μN。2.难点是学生有初中的知识,往往误认为压力N的大小总是跟滑动物体所受的重力相等,因此必须指出只有当两物体的接触面垂直,物体在水平拉力作用下,沿水平面滑动时,压力N的大小才跟物体所受的重力相等。

  • 人教版高中历史必修1抗日战争教案

    人教版高中历史必修1抗日战争教案

    【备课资料】百团大战八路军从8月20日起,在华北敌后出动105个团,约40万兵力,在2500公里长的战线上,发动了规模最大的“以彻底破坏正太路若干要隘,消灭部分敌人截断该线交通”为目的的举世闻名的“百团大战”。八路军提出“不留一根铁轨、不留一根枕木、不留一个车站、不留一个碉堡、不留一座桥梁”的口号,“让敌人用脚同我们赛跑”,“让敌人用牛驴搬炮弹、飞机大炮”。八路军展开攻坚战,端掉敌一系列据点。据有关资料记载,从8月20日到12月5日,在历时三个半月的“百四大战”中,我军共进行大小战斗1824次,毙伤日伪军25800余人,俘日伪军18600余人,缴获了大批武器、弹药和军用食品等;破坏铁路470多公里,公路1500多公里,桥梁、车站、隧道等260余处,使正太铁路停运月余;攻克日伪据点2993个,巩固和扩大了抗日军民占领区。

  • 新人教版高中英语必修1Unit 2 Travelling Around–Listening and Speaking教案

    新人教版高中英语必修1Unit 2 Travelling Around–Listening and Speaking教案

    无论她说什么都不会对我们的安排有影响。Answers: for, arrangement3) Parents arrange everything for their children and spare no effort to pave the way for their success.父母为孩子安排好一切,不遗余力地为他们的成功铺路。4. extremely adv 极其,非常extreme adj 非常的1) Mary found it extremely difficult to get a job.2) I’m extremely sorry to have troubled you.Answers:玛丽发现找工作极其困难。给你添了麻烦,我十分抱歉。3) It had white-painted tunnels and bright red carriages, and proved _________ (extreme) popular with the public.它有白色的隧道和明亮的红色车厢,结果证明它非常受大众的欢迎。Answers: extremelyExercises1. I am continuing to apply_______ jobs though I have failed several times.2. All this had an _______ (extremely) bad effect on the criminal justice system.3. The invention would have wide ______ (apply) in industry.4. She’s happy with her unusual living _________ (arrange).5. I was banging so loudly that I’m ___________ (amaze) that they didn’t hear me.6. You haven’t changed at all you still look ___________ (exact) the same.7. “Was it what you expected?” “Yes, _________ (definite).”8. He was looking forward to______ (work) with the newPrime Minister. Answers: for extreme application arrangement amazed exactly definitely looking单句写作:1. _______________ (你要说些什么) when you get on the platform to accept the reward?2. Since_____________________(我们为这些事情做好了准备), we have nothing to worry about.

  • 新人教版高中英语必修1Unit 2 Travelling Around-Reading for Writing教案

    新人教版高中英语必修1Unit 2 Travelling Around-Reading for Writing教案

    Is there a clear purpose for the trip? :Does each paragraph have a clear main idea? Does the writer use the present continuous tense for future plans?Does the writer use commas, stops, and question marks correctly? Are all the words spelt correctly?Are all the proper nouns capitalized?Revise your draft according to your partner's comments.Step 5:The summary of how to write a travel plan.旅游计划是一种常见的应用文写作。旅游可分为观光游、文化游、美食游及探险游等不同类型,因此旅游计划也要根据不同的旅游目的进行设计。常规的旅游计划需要明确以下几个方面的问题:Travel planWhen will you leave for? Where is your the destination?How will you get there?What will you do there?How long will you there?Is there a clear purpose for the trip? 为了提升旅行计划的层级,还需注意以下几个方面的问题:1.每段是否有明确清晰的主题;2.用一般现在时代替一般将来时;3.用更高级的形容词词汇。例如:表达“好”时,不要总用“nice”,我们还可以用“smart, clean, excellent, exciting, beautiful, wonderful, clever, famous, grand”等表达更具有指向性的词汇;4.用更高级的动词词汇。比如:我们可以用“seem stand, lie .get stay, remain, look . sound, become . keep, grow”等代替"be";

  • 新人教版高中英语必修1Unit 3 Sports and Fitness-Reading for Writing教案

    新人教版高中英语必修1Unit 3 Sports and Fitness-Reading for Writing教案

    Then have them write a short paragraph to describe and explain their changes. After that, get the Ss to exchange their drafts with their partners and use the checklist to give feedback on their drafts, and finally revise it.Step 5 Summary of how to write a wellness book1.健康书的审题步骤:第一步:明确要求该写作属于经验分享,故要用第一人称来写;时态以一股现在时为主。第二步:确定段落该类文章可以从以下三个方面人手:Para.1首先表明写作的目的Para.2自己的做法及心得体会Para.3表示期望及感谢第三步:提炼要点2.健康书常见句式:1) It is an honor for me to share my favorite sport with you,2) It makes me feel relaxed playing with my friends.3) It makes me rid myself of stress while playing with my friends.4) Moreover, it provides me a valuable chance to communicate with others.5) I we eat too little or too much, or if we choose the wrong food, we may become sick.6) We can do something to change the poor situation.Step 6Homework假如你的老师让你在班级Wellness Bok上分享自己的亲身经历及心得,请根据以下要点写一篇80字左右的文章1. 你喜欢的运动是什么?2. 你最喜欢的原因是什么?3. 你参加锻炼的体会。

  • 新人教版高中英语必修1Unit 4 Natural Disasters-Listening and Speaking教案

    新人教版高中英语必修1Unit 4 Natural Disasters-Listening and Speaking教案

    【教材分析】高考听力材料的选用非常重视语言真实性和交际性的原则,语言材料一般来源于实际生活,对话的内容大都取材于日常生活,即衣、食、住、行、工作、学习、天气、生活环境等话题,可分为校园、公共场所、家庭等方面,如: shopping, finding the way, doing one’s homework, seeing a doctor, making a phone call, weather report, asking for different kinds of information等。新教材的特点就是利用生活中真实文本,只是降低难度,让学生注重语言的应用,将是我们高考把握方向的重要因素。【教学目标与核心素养】学习能力目标:在听力当中,学生应该有效规划学习方法,选择恰当的策略与方法。这节课的训练目标是让学生有正确的预测和抓住问题的关键信息,从而用心去听来找寻关键信息。根据生活中实际情况和高考常见语境,我们不难发现提前预测和抓住题干中的w很重要,即what, where, when, why等等。

  • 新人教版高中英语必修1Welcome Unit-Discovering Useful Structures & Listening and Talking教案

    新人教版高中英语必修1Welcome Unit-Discovering Useful Structures & Listening and Talking教案

    常跟双宾语的动词有:(需借助to的)bring, ask, hand, offer, give, lend, send, show, teach, tell, write, pass, pay, promise, return等;基本句型 五S +V + O + OC(主+谓+宾+宾补)特点:动词虽然是及物动词,但是只跟一个宾语还不能表达完整的意思,必须加上一个补充成分来补足宾语,才能使意思完整。 判断原则:能表达成—宾语 是…/做…注:此结构由“主语+及物的谓语动词+宾语+宾语补足语”构成。宾语与宾语补足语之间有逻辑上的主谓关系或主表关系,若无宾语补足语,则句意不够完整。可以用做宾补的有:名词,形容词,副词,介词短语,动词不定式,分词等。如:He considers himself an expert on the subject.他认为自己是这门学科的专家。We must keep our classroom clean.我们必须保持教室清洁。I had my bike stolen.我的自行车被偷了。We invited him to come to our school.我们邀请他来我们学校。I beg you to keep secret what we talked here.我求你对这里所谈的话保密。用it做形式宾语,而将真正的宾语放到宾语补足语的后面,以使句子结构平衡,是英语常用的句型结构方式。即:主语+谓语+it+宾补+真正宾语。如:We think it a good idea to go climb the mountain this Sunday.

  • 新人教版高中英语必修1Welcome Unit-Reading and Thinking教案

    新人教版高中英语必修1Welcome Unit-Reading and Thinking教案

    Step 2 New WordsUse ppt to show some words from the passage.Tell the students to remember the meanings.Step3 Skimming and Thinking1. Skim the text and decide which order Han Jing follows to talk about her first day. Time order or place order?Time order2. What is Han Jing worried about before she goes to senior high school?She is worried about whether she will make new friends and if no one talks to her, what she should do.Step 4 Fast Reading1. Match the main ideas with each paragraphParagraph 1:The worries about the new school day Paragraph 2Han Jing’s first maths classParagraph 3Han Jing’s first chemistry classParagraph 4Han Jing’s feelings about her first senior school dayStep 5 Careful Reading1. Fill in the chart with the words and phrases about Han Jing’s day. Answers: Senior high school, a little nervous; Her first maths class, classmates and teachers, friendly and helpful; Chemistry lab; new; great; annoying guy; Confident; a lot to explore2. Read the text again and discuss the questions.1) Why did Han Jing feel anxious before school?Because she was a new senior high student and she was not outgoing. What was more, she was worried about whether she can make friends.2) How was her first maths class?It was difficult but the teacher was kind and friendly. 3) What happened in the chemistry class? What would you do if this happened to you? A guy next to Han Jing tried to talk with her and she couldn’t concentrate on the experiment.

  • 新人教版高中英语必修2Unit 1 Cultural Heritage-Discovering Useful Structure教案一

    新人教版高中英语必修2Unit 1 Cultural Heritage-Discovering Useful Structure教案一

    This teaching period mainly deals with grammar “restrictive relative clauses.” To begin with, teachers should lead students to revise what they have learned about the relative pronouns and relative adverbs. And then, teachers move on to stress more special cases concerning this grammar, such as the “preposition+ relative pronouns which and whom” and cases where we can omit the relative pronouns. This period carries considerable significance to the cultivation of students’ writing competence and lays a solid foundation for the basic appreciation of language beauty. The teacher is expected to enable students to master this period thoroughly and consolidate the knowledge by doing some exercises. 1. Guide students to review the basic usages of relative pronouns and adverbs of attributive clauses.2. Lead students to learn to use some special cases concerning restrictive relative clauses flexibly.2. Enable students to use the basic phrases structures flexibly.3. Strengthen students’ great interest in grammar learning.1. Help students to appreciate the function of relative pronouns and adverbs of attributive clauses in a sentence2. Instruct students to write essays using the proper relative pronouns and adverbs of attributive clauses.本节语法思考:定语从句在复合句中的作用是什么? 关系词有哪些?定语从句在复合句中的作用相当于形容词,它在句中作定语修饰名词或代词。他们在先行词和定语从句之间起到联系作用,同时在意义上代表先行词并在定语从句中担任一个成分。被定语从句所修饰的词称先行词,定语从句一般放在先行词的后面。

  • 新人教版高中英语选修1Unit 5 Working the Land教案

    新人教版高中英语选修1Unit 5 Working the Land教案

    1. 完成文本主要信息填空(斜体字部分设空):As a witness to farmers’ poor harvests and even a severe shortage of food, Yuan Longping was determined to devote his life to tackling this crisis. After graduation, he realized that what farmers needed most was to boost yields in the fields. Yuan was convinced that the answer lay in the creation of hybrid rice, one characteristic of which is that it usually achieve higher output than conventional crops. However, it was no easy job. The first difficulty he needed to overcome was scientists’ general assumption that this could not be done. Through trial and error, Yuan managed to generate this incredible crop. It is estimated that about 60 percent of domestic rice consumption in China was comprised of crops generated from Yuan’s hybrid strains. His innovation has enabled Chinese farmers to considerably expand their output and helped feed the world. Unwilling to retire early to a life of leisure and unconcerned about celebrity or fortune, Yuan continues to turn one vision after another into realities.2. 模仿写作:Do some research via the Internet and introduce another agricultural scientist, Chen Risheng(陈日胜), using the structure, expressions and writing techniques you have learnt from the text “A Pioneer for All People”.【设计意图】任务1是对文本内容和词汇学习成效的检测。任务2借助文本中学到的词汇和写作手法仿写另一位科学家,提升学生迁移运用词汇、文体结构和写作方法的能力。

  • 人教版高中地理必修1全球气候变化教案

    人教版高中地理必修1全球气候变化教案

    科学家预测,就地区而言,位于低纬度的大部分国家,农作物的产量将减少;而位于高纬度的国家,农作物产量有可能增加。由于不少发展中国家位于低纬度地区,因此,气候变化的这种区域差异性,可能会使发展中国家所面临的问题更为严峻。板书:3全球变暖将加剧水资源的不稳定性与供需矛盾。介绍:全球变暖会影响整个水循环过程,可能使蒸发加大,改变区域降水量和降水分布格局,增加降水极端异常事件的发生,导致洪涝、干旱灾害的频次和强度增加,以及地表径流发生变化。随着径流减少,蒸发增强,全球变暖将加剧水资源的不稳定性与供需矛盾。转折:既然全球变暖会引起很多不利影响,那么作为人类应如何面对这一挑战呢?这就是我们要讨论的第三个问题。板书:三、气候变化的适应对策讨论:请大家阅读结合教材P53气候变化的适应对策部分讨论人类应如何面对全球变暖这一问题 呢?

  • 人教版高中地理选修1天体和星空教案

    人教版高中地理选修1天体和星空教案

    一、 天体1、 概念:宇宙间物质的存在形式。(聚集态的星体及星际物质)注:不作特殊交代的天体均指自然天体2、 几种常见天体的观察(指导学生阅读课本,并总结讲述学生自己平时的生活所见)3、几种常见的天体恒星1) 定义:从质量、组成、形状、发光与否等角度总结交代:数目多少(肉眼所见6000多颗)夜空里的点点繁星差不多都是恒星2)运动特点:(由恒星的“恒”字引发学生分析“北斗七星图形变化”图说明特点)结论:①恒星在不停的运动变化之中②相对位置似乎固定不变,故称“恒星”3)光年----计量天体距离的单位(强调“距离”)分析知识点:①距离地球最近的恒星是 (8分钟)(1. 5亿公里)②距离地球次运的恒星是 (4.2光年)③现在能够探测到的最远天体距离地球多远?星云(指导学生阅读课本与恒星比较总结星云特点,可以从形态、质量、体积、密度、物质组成、观察特点几方面列表比较分析并小结)二、天体系统1、 概念:运动着的天体与天体之间相互吸引、相互绕转而形成的不同级别的系统。

上一页123...201202203204205206207208209210211212下一页
提供各类高质量Word文档下载,PPT模板下载,PPT背景图片下载,免费ppt模板下载,ppt特效动画,PPT模板免费下载,专注素材下载!

PPT全称是PowerPoint,LFPPT为你提供免费PPT模板下载资源。让你10秒轻松搞定幻灯片制作,打造⾼颜值的丰富演示文稿素材模版合集。