说明文用平实的语言客观地解释或探讨各种问题，如机器的制造过程、自然或社会现象产生的原因、工程项目的规划或问题的解决方案等等，介绍自然科学、社会科学领域的最新成果，社会经济发展过程中出现的新生事物等等。说明事物可采用多种方式：例如举例、分类法或类比、对比法，给事物下定义或分析事物产生的原因以及后果。举例说明文使用例子说明事物阐明观点；分解展开法着重于事物的区别、差异，分类展开法则强调事物的相似之处；类比说明事物如何相似，对比说明事物如何不同；因果说明文表明事物发生的原因及结果。除了用文字说明以外，说明文中常常使用数据、图片等资料。

    无论采用什么说明方法，作者都是为了说明事物的本质特征、清晰地展现所说明的事物。

因此，阅读说明文的关键是：抓住事物的特点，即抓住说明对象的本质特征。

    下面具体看看两篇说明文。

    （05 重庆卷 B 段）

    Reading is very important to help you learn English. To learn as much as you can from reading, you need to read different kinds of English. This book provides not only different kinds of English but also a good way to check your reading ability.

There are four parts in the book:

Part 1 is Messages: In this part somebody wants to send information in writing to somebody else.

There is a test on timetables and a test on text messages.

Part 2 is People: In this part all the tests are about people. For example, there is an informal letter between friends. There is formal (正式的) English in biography (传记) . There is a job application as a model to help with your writing, as well as testing your reading.

Part 3 is Places: In this part, too. Many different kinds of English are shown, some informal and some formal. There is the informal English of a holiday postcard. There is also the formal English in a letter of complaint.

Part 4 is Things: You will find some descriptive writing in this part. There are descriptions of clothes and of a computer.

You can do these tests in any order you like, or you can do all the tests with a formal or informal text.

I enjoyed writing this book and I hope you enjoy using it.

解析：这篇文章使用浅显平实的语言详细介绍了这本书的4个部分的内容。说明的重点在书的内容，这本书的特征体现在它的内容。抓住了这一特点，也就读懂了这篇文章，再来做理解题，就容易多了。看看相关的理解题：

59．We can find the introduction to a product in         .

      A．Part 1                 B．Part 2                 C．Part 3                 D．Part 4

60．Which of the following is most probably written in informal English?

       A．A letter of complaint.                 B．A computer handbook.

       C．A letter to a friend.                 D．A story of a president.

61．The passage is most probably written for         .

       A．test designers                  B．students                  C．test-takers                  D．teachers

62．What is the best title of the book?

       A．Test Your Reading                  B．Help with Your Writing

       C．Learn Different Kinds of English                  D．Practise English in Different Ways

（参考答案：DCBA）

（05 山东卷  E篇）

A device that stops drivers from falling asleep at the wheel is about to undergo testing at Department of Transport laboratories and could go on sale within 12 months.

The system, called Driver Alert, aims to reduce deadly road accidents by 20%--40% that are caused by tiredness. Airline pilots can also use it to reduce the 30% of all pilot-error accidents that are related to fatigue.

Driver Alert is based on a computerized wristband. The device, worn by drivers or pilots, gives out a sound about every four minutes during a car journey. After each sound the driver must respond by squeezing the steering wheel(方向盘). A sensor in the wristband detects this pressing action and measures the time between the sound and the driver’s response.

Tiredness is directly related to a driver’s response time. Usually, a watchful driver would take about 400 milliseconds to respond, but once that falls to more than 500 milliseconds, it suggests that the driver is getting sleepy.

In such cases the device gives out more regular and louder sounds, showing that the driver should open a window or stop for a rest. If the driver’s response continues to slow down, the sounds become more frequent until a nonstop alarm warns that the driver must stop as soon as possible.

The device has been delivered to the department’s laboratories for testing. If these tests, scheduled for six months’ time, are successful, the markets will bring the product to market within about a year.

解析：这篇文章说明Driver Alert这一驾驶员警报装置。抓住了它的工作原理、功能作用就抓住了它的本质特点。3、4、5自然段是理解的重点：开车时驾驶员腕带上的警报会每隔4分钟发出声音，驾驶员听到声音按压方向盘作出反应。传感器会探测到从听到声音到作出反应之间的时间差，如果这个时间差大于500毫秒，说明驾驶员疲劳打瞌睡。了解了这个装置的特点，就读懂了这篇文章。看看理解题：

72．According to the text, Driver Alert _____.

       A．aims to reduce tiredness-related accidents

       B．has gone through testing at laboratories

       C．aims to prevent drivers from sleeping

       D．has been on sale for 12 months

73．How should a driver respond to the sounds from Driver Alert?

       A．By sounding a warning.        B．By touching the wristband.

       C．By checking the driving time.       D．By pressing the steering wheel.

74．We can learn from the text that the driver needs to stop for a break when his response time

    is _____.

       A．about 400 milliseconds         B．below 500 milliseconds

       C．over 500 milliseconds        D．about 4 minutes

75．When the driver gets sleepy while driving, Driver Alert _____.

      A．moves more regularly       B．stops working properly

       C．opens the window for the driver         D．sounds more frequently and loudly

（参考答案：ADCD）