2019届一轮复习人教版必修一Unit3Computers教案(1)

2019届一轮复习人教版必修一Unit3Computers教案(1)

Unit 3 Computers教案 ‎ 本堂课包括Warming up 和 Reading 两部分。他们是语言知识和文化意识的输入过程；是语言技能、情感态度和学习策略的培养过程，也是语言输出过程。在整个教学过程中，它是培养学生阅读能力的主要过程，教学重点是阅读技能的培养、交际能力及情感态度的提升。‎ ‎ Warming up部分根据每个人对电脑的看法不同让学生就“Do you like computer?”进行小组探究和讨论，从自身实际出发谈论自己的看法，有助于激发学生对于整个单元的学习兴趣。 Reading部分（Computers）主要讲述的是电脑的发展史，通过一系列问题的设置让学生能够在全面理解文章的基础上提高信息处理、加工和学习的能力。‎ ‎ 教学目标 Knowledge objectives:‎ 掌握以下词语和句型：Calculate, sum, solve, simplify, artificial, intelligence, revolution, reality, totally, application, finance, in common, over time, as a result, from···on, so···that.‎ Ability objectives:‎ 训练学生一定的阅读技巧，使他们掌握一些有效的学习策略，从而提高阅读速度和篇章理解的准确性，并养成一定的自主学习能力；培养学生快速阅读的能力、捕捉信息的能力及运用语言进行交际的能力。‎ Emotion objectives:‎ 通过对“computer”的学习，启发学生思考电脑给我们带来的影响，从而以一种正确的方式利用电脑和网络资源；另外通过电脑的发展历程让学生意识到科技对生活的影响。‎ 教学重难点 ‎1. 教学重点：‎ ‎1.了解计算机的发展过程，进一步认识计算机的演变以及对人类的影响。‎ ‎2.训练学生的阅读技巧，提高学生阅读速度和理解能力。‎ ‎2. 教学难点：‎ 对所获取的信息进行处理、加工和学习，形成有效的学习策略。‎ 教学方法 ‎1.任务型教学 ‎2.课堂操练和小组讨论 ‎3.多媒体教学 教学过程 Step 1 Leading in and Warming up ‎ What can computers be used to do in our daily lives?‎ How do you use computers and the Internet?‎ talk with family / friends play computer games send emails ‎ check emails buy tickets make travel plans check the time of a train watch movies listen to music What English words do you know about a computer?‎ What are they?‎ Step 2 Pre-reading ‎ I am very old now. I was born in China. Many people used me for calculating in the past, but now I am a bit lonely because they don’t like me now. ‎ Do you know who I am?‎ am very small. I can be used for calculating. In China, a lot of students use me when solving mathematical problems. ‎ Do you know who I am?‎ I can be used for calculating. Besides, I can also be used for watching DVD, sending e-mail and communicating through the Internet. However, I am not a PC, because I’m small enough for you to take me with you.‎ Do you know who I am?‎ Step 3 Fast reading ‎ Task 1 ‎ Skimming with the following questions: ‎ ‎1. Where were you in 1642? ‎ ‎2. What happened to you after nearly two hundred years? ‎ ‎3. What were you called in 1936? ‎ ‎4. What happened to you in the 1970s? ‎ Skimming ‎ ‎1. Who is the speak of the text?‎ ‎2. What’s the topic sentence of each paragraph?‎ ‎3. What’s the main idea of the text?‎ ‎4. Put the inventions in time order.‎ ‎1. Who is the speaker of the text?‎ ‎2. What is the topic sentence of each paragraph? ‎ Paragraph 1:‎ Paragraph 2:‎ Paragraph 3:‎ 点拨技巧：topic sentence一般在段首或段末。‎ ‎3. What’s the main idea of the passage?‎ This passage is mainly about the history and the development of the computer.‎ ‎4. Can you put these inventions in an order according to the time when they appeared?‎ ‎( )calculating machine ‎( )PC ‎( )analytical machine ‎( )laptop ‎( )robot ‎( )universal machine Step 4 Careful reading ‎ Scanning Read the passage again and complete the chart below. ‎ Task 1:Finish the timeline TIME EVENTS ‎1940s How big is a computer?‎ The first family of computers was Connected to each other ‎1970s Where are computers used? And what about applications? ‎ Now Computers become a ________ friend and helper of _______ _____. ‎ Task 2: Answer the following questions.‎ ‎1. Why and how did computer change its shape? ‎ Computers changed because the memory of it got improved. ‎ First it was stored in tubes, then on transistors and later on very small chips. ‎ ‎2. What are the applications of computers?‎ ‎①They have been used in communication, finance and trade. ‎ ‎②They have been put into robots and used to make mobile phones as well as help with medical operations. ‎ ‎③ They have been put into space rockets and sent to explore the Moon and Mars. ‎ 1. The history of computers Step 5 Post reading ‎ Summary of the passage.‎ I began as a __________ machine in 1642. It took nearly two hundred years ________ I was built as an analytical machine. I became a “universal machine” in 1936 to ________ any mathematical problem. I was very big at one time. ‎ However, as time _______ by, I was made smaller and smaller. I was given a family __________ by a network in the early 1960s. I was able to _______ my knowledge with others __________ the World Wide Web. ‎ I have been widely used in many fields, such as in communication, _________ trade and medical __________ . I have also been put into robots and space rockets to ________ the Moon ‎ and Mars. I’m glad I am a devoted friend and helper of the human race.‎ Activity : Interview Choose one student as Mr./Miss Computer, and the other students as reporters. ‎ The reporters may ask the following questions:‎ ‎1. Where were you in 1642?‎ ‎2. What happened to you in 1822?‎ ‎3. What were you called in 1936?‎ ‎4. What did you get in 1960s?‎ ‎5. What happened to you in 1970s?‎ Have a debate ‎ Should high school students surf the internet(上网)?‎ Group discussion ‎ Advantages VS. Disadvantages Advantages: ‎ search for information chat with friends shopping online send emails download music and films read news ‎ Other uses:‎ look at photos on the computer read books and magazines Watch movies ‎ Play computer games Listen to music Surf the web for fun Enrich our knowledge about the world Make new friends Using online source to learn English disadvantages The suicide of the boy because of being addicted to computer games Other disadvantages:‎ Too expensive Being addicted to computers can affect your study Some unhealthy information can pollute you Being addicted to computers can affect your physical and mental health Being cheated by others on the computer Commit a crime through computer Step 6 Language points ‎1. In pairs discuss what they have in common. (P.17) 两人一组讨论一下它们有什么相同之处。 ‎ common adj. 普通的，常见的；共有的 n. 共用 A great interest in music was common to them. ‎ 他们对音乐都有着共同的强烈兴趣。‎ It’s common sense to dress more warmly when it gets cold. ‎ 天冷了要穿暖一点，这是常识。 ‎ In common with many people, he prefers classical music to pop music.‎ 和许多人一样，他喜欢古典音乐，而不喜欢流行音乐 ‎【短语归纳】 in common共用(的)；共有(的) ‎ have a lot in common with和……有许多共同之处 have nothing in common with 无共同之处 have something in common with 有一些共同之处 ‎ ‎【2. Although I was young I could simplify difficult sums. 尽管当时我还年轻，但是我能简化一些复杂的数学题。(P18 ) ‎ simplify vt.使简易，简化 ‎ The English in this story has been simplified to make it easier to understand. ‎ 这个故事里的英语得到了简化，使它更容易理解。‎ ‎【拓展归纳】simplified adj. 简易的，简化的 simple adj. 简单的 simply adv. 简单地,仅仅地 ‎ ‎ purify 净化 beautify美化intensify强化classify分类citify 使都市化 ‎【高考链接】‎ ‎（1） (湖北卷) While intelligent people can often ___ the complex，a fool is more likely to complicate the simple. ‎ A．sacrifice　B．substitute C．simplify　D．survive ‎ ‎（2）(浙江卷) Running a company is not ___ a matter of hiring people—they also need to be trained．‎ A. simply B. partly C. seriously D. equally ‎ ‎3. I developed very slowly and it took nearly two hundred years before I was built as an analytical machine by Charles Babbage. (P18)我发育缓慢，差不多到了两百年之后，查尔斯。巴比奇才把我制成了一台分析机。 ‎ ‎ “It was(not)／will(not)be+时间段+before…”意为“用不了多久就……”. ‎ ‎【小试牛刀】 ‎ ‎（1）It’ll be three weeks _ before he comes back _. 要过三周他才回来 。 ‎ ‎（2）He became angry _ before I could explain to him我还没来得及向他解释，他就生气了。 ‎ ‎（3）John thinks it won’t be long ____he is ready for his new job． ‎ A．when B．after C．before D．Since ‎ ‎4. At that time it was considered a technological revolution and the start of my “artificial intelligence”. (P.18) 那时这被当作是一次技术革命，也是我“人工智能”的开始。‎ ‎(1) consider v. 认为；考虑；细想 consider doing sth考虑做某事；‎ consider sb / sth (as) sth认为……是……；‎ be considered to do被认知 ‎ considerable adj. 相当多的 ‎ considerate adj. 考虑周到的；体贴的 ‎ consideration n. 考虑（的事）；深思；体谅 ‎ ‎(2) intelligence n. 智力，聪明 ‎ He is a person of great intelligence. 他是个极聪明的人。‎ intelligent adj. 有智力的，聪明的 intelligently adv. 聪明地 intellectual adj.智力的 adv.知识分子”。‎ ‎【高考连接】 (广东卷完形) I observed a number of _____ children who were taken out of a ‎ special class and placed in a regular class．‎ A. intelligent B. competent C. ordinary D. independent ‎ ‎5. In 1936 my real father, Alan Turing, wrote a book about how computers could be made to work as a “universal machine” to solve any mathematical problem. (P.18) 在1936年，我真正的父亲艾伦·图灵写了一本书，讲述了怎样使我成为一台“通用机器”来解决任何数学难题。‎ 英语中有些动词可接不带to的不定式作宾语补足语，表示动作已完成，但在被动结构中须带上to. ‎ let, make, have; ‎ see, look at, watch, notice, observe, hear, feel, listen to等。‎ They used to be made to work twelve hours a day. 他们过去每天被迫工作12小时。 ‎ The boy was seen to go out the gate. 有人看到这个男孩从大门口跑出去了。 ‎ ‎6. As the years have gone by, I have been made smaller and smaller. (P18， L16-17) 随着岁月的流逝，我被做的越来越小了。 ‎ As we grow older, we get wiser. 随着年龄的增长，我们会变得更聪明。 ‎ 注意：with表示“随着”时，是介词，后不接句子。 ‎ ‎ As the economy develops, more and more waste will be produced. ‎ ‎= With development of the economy, more and more waste will be produced. 随着国家财富的增加，会产生出越来越多的废物。‎ ‎【小试牛刀】 ‎ ‎（1）____ time goes by，Mother's hair has turned grey and the wrinkles on her face deeper. ‎ ‎ A．As B．With C．While D．Because ‎ ‎（2）____ the years slipped by，I thought less about her. ‎ ‎ A．With B．As C．Since D．To ‎ go by 经过（某地）‎ ‎ Don’t let this chance go by. 不要错失这次机会。 ‎ ‎【拓展归纳】by用法 The house stands by the side of the river.房子坐落在河边。 ‎ They had finished their work by the end of last week.到上周末他们已完成了工作。 ‎ I’ll be here by five o’clock this afternoon.我最迟在今天下午5点前到这里。 ‎ My mother often goes to work by bike.我母亲经常骑自行车去上班。 ‎ We learn to swim by swimming.我们通过游泳学习游泳。 ‎ It’s dangerous to judge by appearances.以貌取人是很危险的。 ‎ His horse won by a nose. 他的马以一鼻之差险胜。 ‎ They are paid by the month. 他们所得报酬按月计。 ‎ Are bananas sold by weight? 香蕉是按斤出售的吗？ ‎ ‎【高考链接】‎ ‎(1)（2015陕西卷）The little pupil took his grandma the arm and walked her across the street. ‎ ‎ (2) --- When do we need to pay the balance? ‎ ‎ --- ____ September 30. ‎ ‎【小试牛刀】 ‎ ‎(1)Luckily, the bullet narrowly missed the captain ___ an inch, ‎ ‎(2)—You’re so lucky. ‎ ‎ — What do you mean ___ that? ‎ ‎(3) He __________(build) his own lab by the time he was ten．‎ ‎7. First as a PC(personal computer) and then as a laptop, I have been used in offices and homes since the 1970s. 自二十世纪七十年代以来，我一直被用在办公室和家庭里，先是用作个人电脑，后来又做成便携式。(P18， L16-17) ‎ ‎(1) 现在完成时的被动语态由“have／has been+过去分词”构成。‎ The party has been planned since the new year. 这聚会自新年起就已筹划了。 ‎ ‎【高考链接】‎ ‎ (2013北京卷) Shakespeare’s play Hamlet _________(make) into at least ten different films over the past years. ‎ ‎(2) personal adj. 私人的，个人的，亲自的 personally adv. 就自己而言; 就我个人来说 ‎ personally speaking 我个人认为，以我的看法来说 ‎【高考链接】‎ ‎（2010湖北卷）In this lecture, I can only give you a purely ___ view of how we can live life to the full and make some suggestions about the future. A. private B. personal C. unique D. different ‎ ‎8. As a result, I totally changed my shape. (P18，L19)结果，我完全改变了我的形状。‎ as a result 结果，因此 It doesn’t often rain in summer. As a result, we have to water the vegetable garden. ‎ 这儿夏天不常下雨，因此，我们不得不给菜园浇水。‎ As a result of the accident, he became lame. 因为这次事故，他瘸了。‎ ‎【拓展归纳】‎ as a result(=therefore ) 因此（+结果）（放在句首或句中，用逗号与句子其它部分隔开 as a result of(=because of) 因为（+ 原因(名词，代词，动名词) ‎ ‎ result from 由……导致；源于…… result in …导致…… ‎ He was lazy. As a result, he was late for school. 他懒。结果，他上学迟到了。 ‎ As a result of his laziness, he was late for school.由于他懒。他上学迟到了。 ‎ His laziness resulted in his being late for school.‎ His being late for school resulted from his laziness. 【高考链接】‎ ‎（1）（江西高考卷）My friend Martin was very sick with a strange fever；____, he could neither eat nor sleep. A. as a result B. after all C. any way D. otherwise ‎ ‎ (2) (全国Ⅱ卷)Jenny nearly missed the flight ____ doing too much shopping．‎ A．as a result of B．on top of C．in front of D．in need of ‎ ‎9. But I was always so lonely standing there by myself, until in the early 1960s, they gave me a family connected by a network. (P18)但是我总是孤孤单单地站在那里，直到60年代初，人们才给了我一个用网络联成的家庭。‎ lonely孤独的； 荒凉的，‎ I am lonely without you. 没有你，我是孤独的。‎ She has a soft place in her heart for all lonely people.  她同情所有孤独的人。‎ It felt like the loneliest place in the world. 感觉这就像是天底下最荒凉的地方。‎ ‎【拓展归纳】 ‎ 以 –ly结尾的并非都是副词，有的加-ly的词是形容词（多是名词加-ly）， 如：friendly（有好的），lovely（可爱的）, manly（男子气的），orderly（有秩序的）costly（昂贵的）, brotherly（兄弟般的）, deadly（致命的），lively（活泼的），elderly（稍老的）, likely（可能的），fatherly（父亲般的）,womanly（女子气的）,…等。‎ ‎【近义辨析】lonely, alone ‎ lonely只作形容词用，表示“孤独的、寂寞的”，富有感情色彩。可用作表语和定语。‎ He feels lonely because he has no friends. 他感到孤独，因为他没有朋友。 ‎ This is a lonely mountain village. 这是一个荒凉的山村。‎ alone用作形容词，在句中只用作表语。alone用作副词,表示“单独地、独自”，相当于by oneself。‎ He doesn’t feel lonely when he is alone. 他一个人在家时不感到寂寞。 ‎ He lives alone by now. 到现在他还是一个人生活。‎ ‎(2) by myself我独自地 ‎【拓展归纳】 ‎ by oneself 独自地 of oneself自发地，独自 for oneself 为自己，亲自 enjoy oneself 玩得开心 express oneself 表达自己的意思 help oneself 自取，随便吃 kill oneself 自杀 ‎ ‎(3) connected by a network 做定语 ‎ ‎10. Anyhow, my goal is to provide humans with a life of high quality. (P18， L32-33)不管怎样，我的目标是给人类提供高质量的生活。‎ anyhow = anyway不管怎样. ‎ Anyhow, it’s worth trying. 不管怎样，这事值得一试。‎ It may rain, but we’ll go anyhow. 也许会下雨，但我们无论如何都要去。‎ ‎【近义辨析】 ‎ somehow由于某种未知的原因；不知怎么的；以某种方式；用某种方法；从某种角度。‎ Somehow he was afraid of her. 不知怎的，他怕她。‎ Anyhow/anyway无论如何，尽管如此”, 可以置于句首，句中或句末。‎ I’ve tried, but I can’t open it anyway. 我已经试过了，但无论如何也打不开。‎ ‎【高考链接】 ‎ ‎(湖北高考卷) I'm certain David's told you his business troubles. _____, it's no secret that he owes a lot of money to the bank. ‎ A. However B. Anyway C. Therefore D. Though Step 7 Grammar The Present Perfect Passive Voice ‎【情景感悟】‎ Look at the following sentence, paying attention to the underlined part.‎ Over time I have been changed a lot.‎ Can you pick out more than two sentences in the present perfect passive voice from the reading passage?‎ Underline the use of the present perfect voice in the following poem. Then fill in the chart below.‎ Look at the way your face has been washed. ‎ Look at the way your hair has been combed. ‎ Look at the way your shoes have been cleaned. ‎ You’d better do them again.‎ ‎【名师精讲】‎ 一、现在完成时的被动语态的构成 现在完成时的被动语态由“have／has been+过去分词”构成。‎ ‎[肯定式] have／has been done ‎ Your computer has been repaired．你的电脑已经修好了。‎ ‎[否定式] have／has not been done(haven’t／hasn’t been done) ‎ The desks have not been cleaned．这些课桌还没有擦。 ‎ ‎[疑问式] ‎ 一般疑问式：Have／Has+主语+been done? ‎ 特殊疑问句式：疑问词+have／has(+主语)+been done? ‎ Has the door been painted?那扇门粉刷了吗? ‎ No，it hasn’t．不，还没有。‎ How long has the battery not been changed?电池有多久没有更换了? ‎ 二． 现在完成时的被动语态的用法： ‎ ‎（1）主语是行为动作的承受者。 ‎ The Temple of Zhang Fei has been rebuit. 张飞庙已经过重建。‎ ‎（2）表示一个被动动作发生在说话之前，强调对现在造成的影响和结果。 ‎ The door has been locked. 门已经被锁上了。（我或别人现在进不去）‎ My car has been repaired. 我的汽车以修好了。 ‎ ‎（3）表示一个被动的动作或状态开始于过去，持续到现在，并可能持续下去，常于for或since引导的时间状语连用，或用于How long…? 句型中。 ‎ 经常使用的时间状语还有：so far，up to/till now，over/in/during the past … years，等等。‎ He has been told about it for many times. 有人告诉他这事很多次了。（可能还会有人告诉他）‎ The important problem has been discussed for nearly two weeks. 那个重要的问题已经被讨论近两个星期了。 ‎ The party has been planned since the new year. 这聚会自新年起就已筹划了。 ‎ How long has the car been driven? 这辆汽车开多久了？ ‎ ‎(4) 用在时间或条件状语从句中，表示将来某时已完成的动作，即用现在完成时的被动语态代替将来完成时的被动语态。‎ You shouldn’t leave school before your homework has been finished．你做不完作业不能离校。‎ We’ll start as soon as the work has been finished. 工作一完成我们就立即动身。 ‎ 三． 现在完成时的被动语态使用时注意事项： ‎ ‎（1）“主 ＋ 谓 ＋ 宾”句型变为被动语态。变为被动语态将主动结构中的宾语变为被动结构中的主语。‎ 主动：The manager has not signed the papers. 经理没有在这些文件上签字。 ‎ 被动：The papers have not been signed (by the manager). 这些文件还没有(由经理)签字。 ‎ 四．现在完成时的被动语态使用时注意事项： ‎ ‎（1）“主 ＋ 谓 ＋ 宾”句型变为被动语态。变为被动语态将主动结构中的宾语变为被动结构中的主语。‎ 主动：The manager has not signed the papers. 经理没有在这些文件上签字。 ‎ 被动：The papers have not been signed (by the manager). 这些文件还没有(由经理)签字。‎ ‎（2）“主 ＋ 谓 ＋间接宾语＋直接宾语”。变为被动语态只将主动结构中的一个宾语变为被动结构中的主语，另一宾语不变。如将主动结构中的直接宾语变为被动结构中的主语，间接宾语之前则应加介词to 或for。 如： ‎ 主动：I have told him the good news. 我已告诉过他这个消息。 ‎ 被动：He has been told the good news. 已告诉过他这个消息。 ‎ ‎ The good news has been told to him.这个消息已告诉过他。 ‎ ‎（3） “主 ＋ 谓 ＋ 宾语 ＋ 宾语补足语”，变为被动语态只能将宾语变为主语，原来的宾补保留不动，改称主语补足语。原来为省略to的不定式作宾补的，被动语态中要用带to的不定式。 ‎ 主动：I have found the glasses lying on the desk.我已发现眼镜留在课桌上。 ‎ 被动：The glasses have been found lying on the desk. 眼镜已被发现留在课桌上。‎ 主动：I have heard her say those words. 我听过她说过这样的话。被动：She has been heard to say those words. 听过她说过这样的话. ‎ ‎(4) 现在完成时与一般过去时的被动语态的区别 一般过去时的被动语态所表示的动作或状态与现在的情况无关，而现在完成时的被动语态这强调现在的情况。 ‎ The building was completed last year. 这栋楼是去年完工的。 ‎ The bridge has been completed. 这座桥已经建好了。 ‎ ‎(4) 一些特殊动词, 如borrow, finish, begin, buy, start, return, marry, open, join等构成的现在完成时的被动语态不能与表示一段时间的状语连用。若要表达相应的意思， 则需改换动词或时态。‎ My brother has had(不能用has bought) this bike for almost four years. ‎ How long has this book been bought? ‎ How long ago was this book bought? ‎ ‎【高考链接】‎ (1) ‎ (2015 重庆卷) In my hometown, there is always a harvest supper for the farmers after all the wheat____（be） cut.‎ has been ‎ ‎(2) (2015天津卷) Despite the previous rounds of talks, no agreement_____ (reach) so far by the two sides. ‎ has been reached ‎ ‎(3) (2015安徽卷) It is reported that a space station ______(build) on the moon in years to come. ‎ will be built ‎ ‎(4) (2014天津卷) We won’t start the work until all the preparations _____(make).‎ ‎ have been made （5）. (全国卷) — The window is dirty. ‎ ‎ —I know. It _____ for weeks. ‎ ‎ hasn’t been cleaned ‎ ‎（5）(上海卷) The school board is made up of parents who ______ to make decisions about school affairs. ‎ ‎ have been elected ‎ ‎（6）.（天津卷）In the last few years thousands of films _____ all over the world.‎ ‎ have been produced ‎ ‎（7）.（安徽卷）I like these English songs and they _____ many times on the radio. ‎ ‎ have been taught ‎ ‎【实战演练】‎ I. 用所给（短语）动词的正确形式填空。‎ ‎1. The children _______________ (tell) many times not to go near the river.‎ ‎2. In the last few years thousands of films _________________ (produce) all over the world.  ‎ ‎3. Jenny __________ (make) rapid progress recently and is always being praised by the teachers. ‎ ‎4. Great changes __________________ (take place) in our country since the 2008 Olympic Games. ‎ ‎5. This topic _____________________ (talk about) for two hours. ‎ II. 用现在完成时的被动语态重组下列句子。‎ 1. a new hospital for women and children, build, in Beijing ‎2. more and more trees, cut down, by farmers ‎ ‎3. about 300 buildings and houses, destroy, in the earthquake ‎4. a lot of money, spend, protect the old temple ‎(答案见课件)‎ Step 8 Writing 如何介绍产品类作文 ‎【写作指导】 ‎ ‎1、抓住事物的特征 ‎ ‎ 只有把握住事物的独特性，并以此来展开说明或描述，才能把要说明的对象说清楚。介绍一件事物，要考虑从哪方面着手才可抓住事物的具有代表性的特征。比方说，我们拿起一支铅笔，仔细地观察它，就会注意到它的颜色、形状、长度、锐利程度以及硬度等，这种写作方法尤其适用于描写大家所熟悉的而又具有新的、与众不同的特征的事物。‎ ‎ 2、要遵循一定的顺序 ‎ 写任何文章都要做到条理分明。介绍一件事物，目的是上让读者清楚地了解事物本身的特点、性质以及用途等，因此更需要条理清楚。按人们认识事物的规律进行说明，如由概括到具体，由整体到部分，由现象到本质，由表及里，由原因到结果，由主要到次要，由特点到用途等。 ‎ ‎3、选用恰当的方法 说明事物，我们常采用以下方法； 1)、定义法。定义法的目的是让不知此事物的人对此物有一个起码的了解，以利于下文的展开。有些事物也许不好下个明确定义，但我们可以交待这个事物的背景，来源，或列举出它的一些典型特征，以便让读者明白。‎ ‎2)、举例说明法。举出具有代表性的例子，能够真切地说明事物，化抽象为具体，使段落变得有血有肉，丰富起来。举例时常用的表达有：for example(例如)，as an example of (作为……的例子)，take… for example (以……为例)等。‎ ‎3)、比较法。为了突出事物鲜明的特点，我们常把它与其他事物进行比较。比方说我们想向读者介绍什么是“电脑”，我们可以说“It’s a kind of electrical or artificial (人工的)brain.”这样把电脑和人脑进行了比较，从而使人们对“电脑”有更清晰的认识。‎ ‎4)、细节描述法。作者要提供一些细节，使被描述的对象更加形象具体，从而加深读者的印象。我们还可以通过引经据典(即引用专家、名人等的话语)、列举数字等其他方法说明一件事物，从而使文章更加严密，内容更具有科学性，更有说服力。 ‎ ‎4、运用恰当的语言 介绍事物，文字要力求简洁、明白、准确。比如：We wish to state that this electric car was designed with the idea of safety in mind. 此句冗长，不够简洁，应改为：The electric car was designed for safety. 除讲究语言平实准确的前提下，我们还可以运用描写的方法，来增添文章的可读性。‎ ‎【常用句型】‎ l It is the same size as ... / It is as large as ...‎ l It looks like a ...‎ l It is designed for / to do ...‎ l It can be with me whenever I feel lonely.‎ l It is very good for heart disease.‎ l You can learn how to use an office computer, which will give you convenience to find a good job in a company. ‎ l You can use it to calculate, make notes, call others and type letters, etc. ‎ l Its price is not high, and it has a good look.‎ l Tea has nutritious elements and trace elements, which can make people healthy.‎ l The biscuit is made from flower, eggs, sugar and all kinds of fruit juice. ‎ l It is crisp and delicious, which is made into many different fruit flavors. ‎ l My ideal robot in the future can work as / serve as / be used as ...‎ l A robot is a very human-like servant and it cares for us.‎ l We can imagine a future in which robots will care for our children and develop friendships with us. ‎ ‎【实战演练】‎ 你的外国朋友写信向你了解“茶”这一饮料。请你就题目“茶”写一篇120词左右的英文短文。内容包括： 1)、饮茶源于中国，现已遍及全世界； 2)、中国有许多世界名茶。用不同的方法加工茶，可生产出红茶，绿茶，花茶；保健茶等； 3)、饮茶已成为我们生活的一部分。饮茶可以使人保持大脑清醒，解除疲劳。茶里的营养成分以及微量元素可以使人健康。 ‎ ‎[参考词汇]花茶scented tea；起源 originated ；process 加工；营养成分 nutritious elements；微量元素trace elements ‎ 参考范文：‎ ‎ ‎ Tea Tea drinking originated in ancient China and has spread all over the world. China grows several kinds of the world famous tea. By using different ways to treat and process tea, the Chinese can produce black tea, green tea, scented tea, medical tea and the like. Tea drinking has become part of our life. In China, there are teahouses where people talk to one another tell stories and play chess while drinking tea, People drink tea to refresh the mind and get rid of tiredness. Tea has nutritious elements and trace elements, which can make people healthy. Tea drinking will become more and more popular.‎ Step 9 Homework ‎ Retell the text according to the following clues and then write down your retelling.‎