Ⅰ.说明文的特点

1.说明文的结构

说明文是以说明为主要表达方式的一种写作文体（Writing Style），与其他文体相比较同样由导言段、正文段、结尾段所组成。导言段一般是文章的第一段，提出文章的主题，也就是说，文章想要阐述、说明的主要内容；正文段是文章的主体，可由若干个段落组成，对文章的主题进行展开说明；结尾段是对文章的主题作归纳总结。从英语说明文的结构可以看出，要写好英语说明文的关键在于正文段如何对文章主题进行展开说明。

通常说明文按照一定的顺序排列，如时间顺序、空间顺序、主次顺序、逻辑顺序来介绍解说事物或事理，给人以知识和信息。因此它实际表现着人们认识事物和真理，了解并积累知识和信息的过程，下面结合“My Ideal Career”一文来说明说明文导言、正文、结尾三个部分。

导言即文章的开头部分，主要是提出文章的主题，向读者说明文章的主要内容、事物和对象。通常可为以下一项或几项：一、概述某一现象或事物、事理的基本特征。二、概要介绍事物、事理的总貌或局部特征以引起读者求知的兴趣和积极性。三、提供正确获取知识所必需的背景材料。四、指出使对方认识事物，了解有关信息的目的、要求或依据等。

请看“My Ideal Career”一文的导言：

Many a time in my life I've been asking myself about what career I shall take and what I can do to prepare myself for it.Although my ideas are not consistent， I have now decided on college teaching as my life-long career.

本导言清晰简明地确定了文章的主题，即自己未来理想的工作是什么。读者可从这两句话中抓住文章的主题思想，用词恰当、准确、扼要。

正文段即文章的主体，也称为中心段，一般由一段或若干段组成，主要是对文章的主题、论点、主要说明的事物或事理等诸方面，从不同的侧面、角度对说明对象特点进行分项具体的阐述、解说。正文中段与段之间可使用过渡性词语和连接词巧妙地衔接，使文章更加清晰、严谨、自然流畅。具体方式可分为：一、以时间为顺序，用于重点写事物变化过程的文章。二、按空间顺序，用于介绍自然景物、名胜古迹的文章。三、按主次轻重的顺序，用于重点解说事物效能、用途或全面介绍事物特点的文章。四、按事理逻辑次序，用于需要更加严密地阐述事理或全面解说事物性质状态，以及必须反映事物自身逻辑顺序的文章。请看“My Ideal Career”的正文：

A variety of reasons have led me to choose this occupation over other more lucrative ones. First， teaching means learning. College is a place where I can enrich my knowledge and improve myself.Besides， to make my lectures more constructive and stimulating， I have to read extensively， explore new knowledge and gain a better understanding of the world—the very thing I enjoy in my life.Second， teaching means independence. As a teacher， I am my own boss and free to use my own ideas to make my own decisions. It is a privilege not everyone can have， even those with highly-paid positions. The content of my lessons and the way of delivering lessons largely depend on myself. Finally， I like teaching because it offers a sense of dignity. A teacher is not only a person who passes down knowledge， but a person who plays an important role in the process of students'growing. To be a teacher， I am a person who helps to create and mould students'personality. I am proud of such a noble career.

正文按事理的逻辑次序说明了选择大学教师作为自己的终身职业的三个主要原因，作者使用了First、 Second、 Finally把正文阐述得有理有据，层层递进，极具逻辑性和说服力。

结尾是文章的结束，主要是对说明对象进行总的概括性说明，以达到归纳文章重点和深化主题的作用。其具体内容可分为以下几项：一、解释说明事物按逻辑顺序达到的终结点。二、强调掌握有关知识或信息的重要性。三、介绍当前对该对象的总体认识水平，展望研究前景。四、说明或重申使对方掌握该知识或信息的目的、要求或依据。五、总括或重申对象的全貌或基本特征等。请看“My Ideal Career”的结尾：

However， teaching is a demanding job. Only a person with rich knowledge can make a qualified teacher. In order to be a college teacher， I shall study hard not only in class， but also in daily life. Moreover， I shall train my patience， improve my handwriting， and enlarge my knowledge.

结尾段开头使用了一个转折词However，紧接着作者又写到teaching is a demanding job，使读者马上意识到了这份工作的分量及要求，作者只用了4句话简单扼要地说明了为理想的实现该做的几点准备工作。

2.说明文的语言特点

与英语记叙文和英语描述文相比，英语说明文的语言特征并不那么明显。但尽管如此，也还是有一些语言现象在英语说明文中经常出现。

1）时态相对较为统一：多用现在时态

由于说明文往往是对客观事物或事理的一种介绍与解释，而这种客观的介绍与解释一般是不随时间和空间变化而改变的，比如：说明早锻炼的好处，介绍猫的胡子的功能，解释臭氧层对人类生活的影响等等，是不受时间和空间影响的。因此，尽管有时为了特殊表达的要求，会在个别地方采用其他时态，英语说明文的基本时态还是一般现在时。如：

A Dog

A dog is a kind of animal. It often lives with people at home.It's one of the pet animals. Many people like to keep a dog for pleasure because it is clever and it can understand them. People feed the dog and build a house for it. Dogs can do lots of things for people. In cities， people keep a dog not only for pleasure but also for safety. A dog can be a good guard. In the country， farmers like to keep dogs for pleasure too. Besides， some of the dogs can help farmers to look after animals， such as sheep and pigs. Dogs can be a great help to army soldiers and policemen. Dogs often do important work for them. So dogs are really our good friends， and we must take good care of them.

2）采用客观表述，避免主观色彩

由于在很多情况下，说明文是对客观存在的说明与介绍，因此，语言的表述也应该尽可能地给人以客观可信的感觉。如：

（1） I think that getting up late is not always a bad thing.

（2） It is said that getting up late is not always a bad thing.相比之下，例（2）的语言要比例（1）的语言客观一些，容易让人接受一些。如果再作一些表述上的改动：

（3） Getting up late is not always a bad thing， according to Franklin Smith， a well-known psychologist in Stanford University.

引进著名人士作为信息的来源，可以使想要说明的内容更具有说服力。如果我们将例（3）中的always再改为necessarily，就可使整个句子更客观、委婉，便于为读者接受：

（4） Getting up late is not necessarily a bad thing， according to Franklin Smith， a well-known psychologist in Stanford University.

在英语中，采用被动语态，引进权威的信息来源以及选用委婉的词语是使说明文避免主观色彩，增加客观性，从而为读者接受的重要语言手段。

3.说明文的注意事项

说明文必须做到解说清楚明晰，因此，撰写说明文时需注意以下几点：

1）目的明确，解说性强

说明文在表达方式的运用上要以说明为主，是对事物的性质、形态、特征、结构、功能、成因、结果或发生发展过程直接予以直线的解释说明，将事物或事理深入浅出、条理分明、例证充分、合乎逻辑地提供给读者，一般不需要形象描绘。

2）具有知识性、信息性

说明文体的使用目的是给人以比较系统的知识和对客观情况的认识，消除人们在某些理解上的误区，因此，它是人们了解情况、认识事物的重要工具。

3）主题清晰、客观性强

说明文通过解释、介绍、阐述事物或事理的方式给人以知识和信息，教人以应用。作者要主题清晰，以事实为依据，如实反映事物或事理。写作时一般不带强烈的色彩和个人的主观倾向。

4）语言通俗易懂、简明、朴实

说明文写作要注重冷静、科学、客观，实事求是，无需有个人的感情流露，在表达方式上，应以说明为主并辅以描写和议论。写作目的在于给人以知识和信息，帮助人们准确认识客观事物。在写作态度方面，重在对客观事物、事理进行准确、客观、冷静地介绍及解释，不需要确立论点，也不需写作者个人的思想倾向。如：

The Potential of Internet Education

Internet is getting into people's life and becoming more and more popular. Experts are now working on setting up a national long-distance educational system in China to provide educational opportunities via Internet.

In reality， the educational system via Internet plan has been taking shape. Some universities have already got involved in regional long-distance education， catching the attention of many educators and computer experts worldwide. Others have just connected their campus computers for teaching and research， and provided more opportunities for learners.

The Internet education will be developing dramatically. It's estimated that computerized long-distance teaching networks will be available by 2010 for postgraduate education， vocational programs， teachers'training and employees'training. Moreover，it will soon cover all the corners of the globe and eventually win the worldwide popularity.

此文是典型的三段式结构说明文，文章主要说明互联网教育的潜在能力。引言段介绍了互联网正在普及，专家们正在为提供更多的教育机会而致力于建立国内的远程系统，主题明确。正文段介绍了我国互联网教育现状及在一些大学中已初见成效，层次分明。结尾段展望了互联网教育鼓舞人心的发展前景，语句连贯。因此，本说明文短小精悍，很有感染力。

4.说明文常用写作方法

1）例证法

这是用具体例子来说明人或事物的特征、本质及其规律的方法，所用例子必须有代表性、典型性，能体现人或事物的本质特征。这是用特殊来说明一般的方法。通常在主题句后，用For example或For instance等短语引导出具体的例子。如：

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

下定义就是给说明对象一个明确概念。这是科学而严密的说明方法。它既能揭示事物的本质特征，勾勒其大概，描绘其轮廓，同时也能确定事物的范围和界限。下定义是多方面的，可以给人、事物、思想等下定义。如：

An ideal teacher must have the following characteristics. He should know his subject， but he can make mistakes if he is not 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

分类法是对同属不同类或同类而不同种的人或事物，根据不同性质进行分门别类地说明的方法。分类是人类认识客观世界的重要手段之一。分类必须遵守分类规则，使分类对象具有统一属性，依据同一分类标准，并使分类的子项相互排斥，不互相包蕴。如：

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

事物变化的原因和结果是紧密相关的。如果某个现象的存在必然引起另一个现象的发生，那么，这两个现象之间就具有因果关系。因果关系包括“由果推因”（由结果去推测原因）和“由因推果”（由原因去推测结果）两种情况。因果关系符合人们的日常思维逻辑，因而在写作中得到广泛应用，常用because， as， since， so， now that， if... then， the reason is that…等表示因果关系。如：

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 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.

本段中，第一句为主题句，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，是一篇典型的先果后因的说明文段落。

5）比较对照法

有意识地把两种相反、相对的事物或同一事物相反、相对的两个方面放在一起，用比较的方法加以描述或说明，指出其相同点，这种写法叫做“比较”；指出其不同点，叫作“对照”。比较和对照各有不同的侧重，但两种方法经常结合使用。

进行比较对照通常有两种方式：一、采用“先A后B”的结构，即A1，A2，A3…… ； B1，B2，B3……二、采用“AB交错”结构，即A1，B1，A2，B2，A3，B3……

第一种方式采用先A后B的结构实际上是把一个段落（或一篇文章）分割为两部分，先全面讲A，再全面讲B，这样做较难收到强烈的对比效果。多数人认为第二种方式比较好，因为把对比的双方A B逐点交错，可以避免行文的单调沉闷，对比的效果也会更鲜明突出。如：

It is easy to be a winner. A winner can show his joy publicly.He can laugh and sing and dance and celebrate his victory. People love to be with winners. Winners are never lonely. Unlike winners， losers are the lonely ones of the world. It is difficult to face defeat with dignity. Losers cannot show their disappointments publicly. They cannot cry or grieve about their defeat. They may suffer privately， but they must be composed in public. They have nothing to celebrate and no one to share their sadness.

这段采用先A后B的对照方式，阐述胜利者和失败者的不同特征。这种写法较易操作，但行文往往比较平淡单调。再来看看AB交错的比较方式：

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，给读者印象也更鲜明突出。6）过程分析法

过程分析法就是把事物发展过程分为若干步骤，然后逐一加以分析说明。这种写法在说明文中使用得相当广泛。过程分析与叙事和因果关系等写法有密切关系，但彼此又有明显区别：叙事研究的对象是“What happens”；因果关系研究的对象是“Why does it happen”；而过程分析研究的对象是“How does it happen”。如：

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。7）统计法

统计法是运用数据来表明事物的本质和特点，准确合理的数据使文章精确可信。如：

Nearly half of all Americans over age 20 wear a brace or denture， and more than 20 percent have complete upper and lower denture. By age 50， one out of every two persons has gum disease.And it seems sensible to wait. One quarter of all marriages between people under twenty-one end in divorce. In Britain in 1973， there were 124,248 divorces.

说明文的说明方法除以上介绍的常见的几种外，还有分项法、列举法、比喻法及引用法等。只有综合运用多种说明方法，才能多角度、多层次地全面、清晰、准确地展示客观食物的本来面貌。还必须说明的是，在实际写作中，我们很少单独采用上述几种方法中的某一种。不少段落（或文章）的写作都是综合使用各种不同的写作方法。同时还应明确，在写作中有意识地侧重使用某一种方法是有好处的。