Ⅱ.说明文的基本类型

1.描述性说明文

描述性说明文通常在文章的第一段对现象加以描述，在正文部分详细分析产生现象的原因和危害，在结尾段提出解决问题的措施和方法。如：

Drug Abuse

Drug abuse among young people has become more and more prevalent over recent years. （主题句）Statistics show that the number of youth drug users almost doubles in the past three years.（数据支撑）It is vital to analyze why drugs are so attractive to young people and what can be done to combat it.（结论）

Firstly， teenagers are under increasing pressure—this may be peer pressure or pressure to succeed. Drug use may help them escape reality， forget their problems， or simply feel more accepted by their friends. （原因1） In addition， through the media we are exposed to information that glamorizes drug use and makes it look attractive， particularly to young people. （原因2） Furthermore，teenagers are usually naturally curious about drugs， and drug dealers can take advantage of this curiosity for their own profit.（原因3）

High fines and prison sentences should also be imposed on drug dealers and users. （措施1） However， it is my own personal view that prevention is better than cure and so a good education program about the dangers of drug abuse is one of the most important steps any government should take. （措施2）

2.比较性说明文

比较性说明文用于比较两种或几种类似的事物，要求通过比较它们各自的优点或缺点，说明作者自己的看法，并加以论证。这种文章的基本结构如下：Paragraph 1： phenomenon（现象）；Paragraph 2： advantages（优点）； Paragraph 3： disadvantages（缺点）；Paragraph 4： comments（结论）。如：

Mobile Phone

A mobile phone is getting increasingly popular. （主题句）Statistics show that eight out of ten college students have got one.（数据支撑）However， as is the case with many issues， a mobile phone has both positive and negative aspects. （承上启下）

The fact that a mobile phone allows a person to be contacted at any time can in itself be a disadvantage. For instance， an employee may， via the mobile phone， be constantly available to his employer and feels that he never leaves work. This may cause distress. （缺点1） Another disadvantage is the perceived health risks associated with its use. Some people believe that using mobile phones for long periods can damage the brain.（缺点2）

There is no denying that a mobile phone has both benefits and drawbacks but on balance perhaps the advantages of a mobile phone outweigh its disadvantages since a mobile has become an integral part of modern life. （结论）

3.图表性说明文

图表说明文也属于说明文的类型，图表作文是采用统计数据表（table），坐标曲线（graph）或圆形饼图（pie chart）等资料数据来阐述论题的作文。也是科技文献中常用的一种表达手段。图表作文要求利用图表，表格和曲线图作为作文提示，并以此为依据要求用简洁生动的语言，把图表中给定的信息完整而又准确地表达出来。图表作文不但要求作者具有一定的英文写作能力，而且要求具有较强的观察力，分析力和充分的想象力。图表作文有以下两种类型：

1）要求客观陈述图表信息内容，侧重对比分析和说明资料数据之间的关系上。最后分析和查找出规律，归纳得出结论。如：

Directions: For this part， you are allowed 30 minutes to write a composition of no less than 100 words on Changes in the use of transport. Study the following table carefully and your composition must be based on the information given in the table.

Changes in the Use of Transport

According to the graph， there are many dramatic changes in the use of transport from 1988 to 2008. In 1988， only 10% of the people drove to work， but ten years later， about one quarter of them owned a car. What surprises us is that in 2008， the number of people who went to work by car jumped to 30% ， a 20% increase compared with 1988. However， during the same period， there was a gradual decline in the use of bicycle and on foot， with the number dropping from 30% in 1988 to 20% in 1998. What's worse， in 2008， only about 10% of the people prefer to cycle or walk to work.

2）要求深入分析原因，先阐述图表数据所反映的问题，进而筛选出有关的数据资料进行的分析讨论，最后找出解决问题的方法。如：

Directions: For this part， you are allowed 30 minutes to write a composition of no less than 100 words on Changes in People's Diet. Study the following table carefully and your composition must be based on the information given in the table.

Changes in People's Diet

As can be seen from the table， great changes have been taking place in people's diet over the period from 1986 to 1990. The consumption of grain has decreased by 4% ， while the consumption of high quality food， such as milk and meat， has increased steadily.

There are chiefly two reasons， I think， for the changes. In the old days， people could not often afford meat and milk whose price was only within reach of well-to-do families. But now， with the improvement of living standard， most people have enough money to buy them. And people of today also pay more attention to nutrition. They want to eat not only more but also better. They are seeking the most reasonable diet structure which will do good to their health.

In short， with the improvement of people's living standard，changes in their diet will be more obvious and great.