篇一：学习写说明文
说明文是一种以说明为主要表达方式，介绍事物，阐明事理的文章。常见的说明文有说明书，解说词，科学小品（又名知识小品）等。
说明文的主要特点有：说明的中心要鲜明突出；抓住事物的主要特征和事物的本质，正确客观地对事物进行介绍、说明，具有很强的科学性。根据事物本身的条理，或按事物的时间顺序说明事物，或按方位顺序说明事物，或按性质类别说明事物，或按成长规律说明事物??富有条理性；语言力求准确、简明、通俗、生动。
说明文常见的说明方法有：下定义，分种类，打比方，举实例，列数字，作比较，引资料等等。说明文以说明作为最主要的表达方式，在说明中适当运用记叙或描写成分，采用比喻，拟人等修辞手法，可以引起读者的兴趣，增强说明内容的具体性和生动性。
说明文根据说明的对象不同可以分作两大类：一类是说明具体事物的，包括说明事物的特征的，也包括说明事物的变化；另一类是阐明抽象事理的。
下面根据说明文的不同类别，分别介绍写说明文的方法。
【范例解析】
一、说明具体事物的说明文。
题目：《我的笔记本电脑》
我家有一台联想笔记本电脑，长约30厘米，宽约24厘米，厚约6厘米，和一本大笔记本差不多。它虽然是电脑的微缩型，但价格可比普通电脑贵了差不多一倍，可功能却一点都不少。
笔记本电脑通体漆黑，像一块黑绸缎一样。面板上有一块legend的联想标志闪闪发光。主体四周有一些可以打开的.小门，可以放入软盘、光盘；还有许多输入，输出口，可以插入电线，连接许多复杂的小配件，如稳压电源，耳机，“猫”（调制解调器）等。
打开盖板，只见盖板里面一块微型液晶板映入眼帘，原来这就是显示器。主体上面是排列非常紧凑的键盘，键盘的下方有一个感应器，具有鼠标的功能。键盘的上面有两个喇叭，以至电脑的背景音乐十分宏亮。左侧面还有一个开关，这是电源总开关，控制着电脑的开和关。右侧面还有一个插口，是鼠标插入的地方。 我非常爱用它来休闲。打开它，我就有一种新鲜感。用鼠标在因特网上漫游，可以看到很多奇妙的趣文，十分舒坦。它还能帮助我学习文化知识。记得有一次，我在做数学题时，遇到了一道难题，便请教这位“老师”。它先“讲”出解题的思路，然后列出几种解题算式。让你选择一种正确的。你如果答得好，它还会放一段动画片奖励你呢！有时我也玩游戏，一个人太没意思了，它就会和我“并肩战斗”。
这个电脑可以储电，因为主体体中有蓄电池。白天不在家，就插上插头，给它补补“力气”，也挺有趣的。充满电的它无需电源插头，直接可以使用。与普通电脑相比，它体积小，便于携带，所以人们称它“便携式电脑”。
笔记本电脑是我的好老师，也是我的好伙伴，更是世界高科技发展的象征。
【评析】 这是一篇介绍电脑的说明文。文章抓住笔记本电脑体积小，携带方便的特点，按由表及里的顺序，恰当地运用了多种说明方法，清楚明白地说明了笔记本电脑的构造，功能及操作使用方法，条理清晰，具体生动。
篇二：电脑说明文
电脑
五年级 陈丽媛
提起电脑，相信大家都非常熟悉。电脑又叫电子计算机。如今，随着科技的发展，电脑已走进千家万户。
电脑一般分为两大类；一类是个人电脑，个人电脑有台式的，笔记本的，最新式的是平板的。另一类是超级电脑，每秒的运算速度在亿次以上，主要用在银行、科研、军事等方面。
电脑由硬件系统和软件系统组成。电脑的硬件系统主要由主机、显示器、键盘、鼠标、音箱、摄像头等组成。主机就是电脑的主管，就像我们的头脑，控制着电脑每天的工作。显示器就像我们的眼睛，把所有工作的成果展示给我们看。键盘上有26个英文字母键，方向键，数字键和几个重要按键，是电脑主要的输入设备。鼠标就像一只老鼠似的扒在桌子上，可是作用非常大，可以灵活地指挥各种应用程序。音箱可以带领我们进入美妙的音乐世界。摄像头可以让我们足不出户，与世界各地的人们交流。电脑的软件系统分为两类；一类是操作系统软件，主要有windows操作系统和Linux操作系统等，最原始的是dos操作系统。它们是计算机底层的系统软件，负责管理、调度、指挥计算机的软硬件资源使其协调工作，没有它，任何计算机都无法正常运行。它在资源使用者和资源之间充当中间人的角色，举个例子，一个用户（也可以是程序）将一个文件存盘，操作系统就会开始工作：管理磁盘空间的分配，将要保存的信息由内存写到磁盘等。当用户要运行一个程序时，操作系统必须先将程序载入内存，当程序执行时，操作系统会让程序使用CPU。另一类是应用软件，可以办公，也可以游戏，还能保证安全等等。
电脑的用途很多：可以上网，例如聊天、发邮件、听音乐，玩游戏、登Q、查资料等；可以管理资料，比如学校的图书室里的电脑是用来登记图书借出去情况的；可以记帐，比如超市里的计算机，就是拿来记帐的；还可以控制生产，比如水泥厂里的电脑能自动控制生产。瞧，电脑真是各方面的能人！
电脑与人们的生活息息相关，让人们的生活变得更美好。
指导老师 林蔚文
篇三：说明文是以说明为主要表达方式用来说明事物
说明文是以说明为主要表达方式用来说明事物，阐明事理的一种文体。它通过揭示概念来说明事物的特征、本质及其规律性，给人准确的科学知识或正确思想。一般可分为实体事物说明和抽象事物说明两大类，词典、教材、论文、实验报告、产品说明书、广告、解说词及科学小品等都属于说明文。
按写作方法,英语说明文主要分为下面六种类型
1.例证法 2.定义法 3.分类法 4.因果关系法 5.比较对照法 6.过程分析法
1.例证法
Our life today depends very much on energy. For example, machines have made our life easier than it used to be. The machines use energy, and energy is needed for heating, lighting, communications, carrying goods-everything. Factories use a great deal of energy to make the things that we use and buy and sell.
这段主要是讲能源问题。第一句为主题句,概括地说出"我们目前的生活很大程度上依赖能源"。接着用举例的方法从三方面说明能源的作用。
2.定义法
An ideal teacher must have the following characteristics. He should know his subject, but he can make mistakes if he is willing to learn. His personality is as important as his scholarship. An ideal teacher must be enthusiastic. He should be a bit of an actor and he shouldn't be afraid to show his feelings and express his likes and dislikes. An ideal teacher is one who grows, learns, and improves himself along with his students.
本段的展开是通过对"一个模范教师"下定义的方法,关键词"ideal teacher"在文中多次重复,能加深读者的印象。
3.分类法
As far as political views are concerned, people fall into three categories. First are the conservative people. Conservatives are opposed to sudden or great changes. Second are the liberal people. These people are in favour of progress and reform. But their opinions often seem too idealistic. Third are the moderate people. The moderates keep everything within reasonable limits. They are more practical in this hard world. In my opinion, most people seem to belong to this group.
本段把人按政治观点分为三类:保守派(conservative people)、自由派(liberal people)和温和派(moderate people),并对他们各自的特征进行了简要的分析。
4.因果关系法
Of the four seasons, I like spring best. I prefer spring because it is a season of much joy and gaiety. New life bursts out everywhere. Plants wear a green coat again and colourful flowers blossom in gardens and mountains. The old come outdoors for fresh air and the young plan for outdoor activities. Life becomes so energetic and happy.
第一句为本段主题句,末句是总结句。在主题句后, 作者用了四个句子阐述自己喜欢春天的理由。
5.比较对照法
I like having a twin sister. When she's happy, I'm happy. When she feels unhappy, I feel the same. Often, I know what she's going to say. Sometimes, I know what she's thinking. I like what she likes. I hate what she hates. We like the same music, the same food and the same books.
这段采用AB交错的比较方式,阐述孪生姐妹的相同特征。这种写法较流畅自然,给读者的印象也更鲜明突出。
6.过程分析法
There are several steps to plant a tree. First, dig a hole large enough for the tree, but the hole should not be too deep. Second, put the tree in the hole so that it is straight. Third, put the earth back into the hole again. Push it down hard with your foot several times. Finally, water the tree well, as often as possible.
这段分析了植树过程中的几个步骤。全段层次分明,连接词语(first, second, third, finally)的使用加强了语句的连贯性。
Exercises
例１ 请根据Wang Hua 在学骑自行车时的几个步骤，写一篇短文，说明他是任何学会骑自行车的．
参考词汇： handle-bars 自行车把手 pedal 踏板 saddle 车座
Wang Hua is learning to ride a bicycle. Let’s watch him and see how he can get on his bicycle. He put his hands on the handle-bars. He puts his left foot on the left pedal, then he pushes himself hard forward with his right leg. Now he can move on together with the bicycle and his whole body is now on the bicycle. Then, he raises his right leg over the saddle and lower himself on the saddle. Now, he is on the bicycle and stepping the pedals hard with both legs. And the bicycle is going forward.
例2
请写一篇短文介绍如何乘坐伦敦地铁．
内容提示如下：
1. 在售票处（booth)购买辅币（token)需30便士．
2. 在入口处将辅币投入狭孔（slot)，你就可以走下地铁．
3. 在站台等车时，要站在白线以外．注意你要去的方向．不要站错站台．
4. 上下车应迅速，因为车门关闭很快．地铁内规定不准吸烟．
注意：短文的意思要连贯． 字数：100个左右．
If you want to travel by underground in London, you should first find the nearest underground entrance and buy a token for 30 pence in the booth. After you drop the token into the slot at the entrance, you can walk down the stairs. Stand back of the white line while waiting for the train on the platform. Make sure that you are on the right side of the platform for your train. When the train arrives, get on or get off quickly because the doors of the train close quickly. Smoking is not allowed in the underground.
例3
家用电脑体积下，价格低，造型优美，简单易用，使用方便，灵活；可用于计算，记事，打电话，打印信件；儿童可用它来学英语，做游戏． 你通过家用电脑能学会怎样使用微机；为将来寻找工作提供便利；电脑工作比人快数百倍；我们已经得到电脑的巨大帮助． 请根据以上内容写一篇介绍家用电脑的说明文． 字数120左右．
A Family Computer
A family computer is small. Its price is not high, and it has a good look. It can be used easily. You can calculate, make notes, call others and type letters, etc. Also, children can learn English or play games with it. Besides, you can use a family computer as a training computer. You can learn how to use an office computer, which can give you convenience to find a good job in a company. Computers can work hundreds of times faster than humans. We have been greatly helped by
computers.
例 4
请以The Importance of Trees 为题写一篇短文，说明保护森林的必要性．
1. 说明树木的主要用途：提供木材；吸水，防止水灾，旱灾；净化空气，美化生活．
2. 滥伐树木的危害；无计划砍伐造成水土流失，土壤沙化，造成水灾．
3. 每年都应植树造林，使其为人类更好服务等等．
字数：100左右．
As we all know, trees are very useful. They are of great benefit to man as follows. First, trees provide us with wood and other products. Second, their roots can allow the rain to sink in and keep the soil, so they help to prevent droughts and floods. Trees can help clean air and beautify life.
Unfortunately, nowadays in many parts of the world lots of people fail to realize the importance of trees. They have cut trees down in large numbers without a plan, which makes the soil washed away. They don’t know where there are no trees, the rain washes away the surface of the soil and this causes floods.
We ought to plant trees each year and carefully look after new trees in order not to make the forest slowly disappear. Only in this way can we make the forest serve man forever.
例 5
根据下表格提供的信息，请你推荐两本学中文的词典．
Dear Steve,
I’m pleased to learn that you and your classmates are learning Chinese. I’d like to recommend the following two dictionaries. The English- Chinese Chinese-English Dictionary is really a good one for beginners. It has 18,000 English words and 20,000 Chinese words. Besides plenty of examples, it has many notes telling you how to use a word. Xinhua Dictionary is the most popular Chinese dictionary, and it has a vocabulary of 10,000 words. It may also be useful to some advanced learners of Chinese. Of the two, ECCED is the more expensive, costing 52 yuan, and XD costs 11 yuan.
Please let me know if you want me to buy these dictionaries.
Yours, Li Yua
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