科普知识型科普类文章主要包括自然科学类、前沿科技发明类和医疗卫生类等，其取材密切联系当前经济和科技等方面的变化，以介绍某一科学现象居多。
科普类文章具有结构严谨、逻辑性强等特点。
其主要命题形式有事实细节题、词义猜测题、推理判断题以及主旨概括题等，其中推理判断题居多。
从词汇角度来看，在科普类文章中，词汇的意义比较单一、稳定、简明、不带感情色彩，具有单一性和准确性的特点。
从语法和句子结构方面看，句子结构较复杂，长难句较多，语法分析较困难。
文章中常用被动语态、定语从句等。
科普文常用的修辞手段有：(1)下定义：有时为了突出事物的主要内容或主要问题，往往用下定义的方法使读者对被说明的对象有明确的概念。
(2)举事例：举出有代表性的恰当的例子，能够反映一般的情况，真切地说明事物的特征。
(3)做比较：选择有外部或内部联系的事物进行比较，往往能增强说明事物的效果。
(4)打比方：适当运用比喻，能够增强说明的形象性和生动性。
科普说明文在结构上常采用的写作方法有：(1)总分式。
在说明事物或事理时，段落(层次)之间有一个总分关系，表现为由总到分、由分到总。
(2)承接式。
各层之间按照事物的发展过程，或者按时间、因果、条件等关系安排，前后相互承接。
(3)递进式。
后面内容在前面内容的基础上进一步说明，各层之间的关系由浅入深。
文章的命题除了遵循科普阅读的命题方式外，还经常考查文章的篇章结构和修辞手法。
【重庆卷】Almost every machine with moving parts has wheels, yet no one knows exactly when the first wheel was invented or what it was used for. We do know, however, that they existed over 5,500 years ago in ancient Asia.The oldest known transport wheel was discovered in 2002 in Slovenia. It is over 5,100 years old. Evidence suggests that wheels for transport didn't become popular for a while, though. This could be because animals did a perfectly good job of carrying farming tools and humans around.But it could also be because of a difficult situation. While wheels need to roll on smooth surfaces, roads with smooth surfaces weren't going to be constructed until there was plenty of demand for them. Eventually, road surfaces did become smoother, but this difficult situation appeared again a few centuries later. There had been no important changes in wheel and vehicle design before the arrival of modem road design.In the mid-1700s, a Frenchman came up with a new design of road—a base layer (层) of large stones covered with a thin layer of smaller stones. A Scotsman improved on this design in the 1820s and a strong, lasting road surface became a reality. At around the same lime, metal hubs (the central part of a wheel) came into being, followed by the pneumatic tyre(充气轮胎) in 1846. Alloy wheels were invented in 1967, sixty years after the appearance of tarmacked roads (柏油路). As wheel design took off, vehicles got faster and faster.64. What might explain why transport wheels didn't become popular for some time?A. Few knew how to use transport wheels.B. Humans carried farming tools just as well.C. Animals were a good means of transport.D. The existence of transport wheels was not known.65. What do we know about road design from the passage?A. It was easier than wheel design.B. It improved after big changes in vehicle design.C. It was promoted by fast-moving vehicles.D. It provided conditions for wheel design to develop.66. How is the last paragraph mainly developed?A. By giving examples.B. By making comparisons.C. By following time order.D. By making classifications.67. What is the passage mainly about?A. The beginning of road design.B. The development of transport wheels.C. The history of public transport.D. His invention of fast-moving vehicles.【语篇解读】本文是一篇说明文，题材是车轮。
全文讲述了车轮的发展历程以及道路设计对车轮发展的影响。
【解析】64. C。
推理判断题。
难度：中等。
题干关键词为didn’t become popular，定位第二段。
根据This could be because animals did a perfectly good job of carrying farming tools and humans around.（这或许是因为动物在拉运农具人们的方面做得不错。
）可知由于当时动物使用的方便让轮子没能够普及。
解题思路：干扰项排除：考生易选C项，根据squirming excitedly来判断。
这里尤其要注意excitedly，只是表达人物的心理，和调皮是没有关系的。
选quiet，是忽略了squirming excitedly的表达。
65. D。
推理判断题。
难度：较难。
根据题干关键词road design，定位第3段There had been no important changes in wheel and vehicle design before the arrival of modem road design.（在现代道路设计之前，轮子和交通工具的设计都没有重大变化）。
第4段接着讲述了随着道路设计的进步，各种新型的轮子(包括充气轮胎)随之发展，而且也促进了车辆的发展。
由此可知，道路设计的发展促进了车轮的发展。
干扰项排除：考生一定要先抓住关键词所在的句子，有的考生选B、C项意义相近，而A项文中根本没有提及。
66. C。
推理判断题。
难度：较易。
根据第四段时间数字，In the mid-1700s、in the 1820s、in 1846、in 1967，只有C项符合。
67. B。
主旨大意。
难度：中等。
全文讲述了车轮的发展历程以及道路设计对车轮发展的影响，故选C项。
解题思路：【难句学习】1. Almost every machine with moving parts has wheels, yet no one knows exactly when the first wheel was invented or what it was used for. 翻译：几乎每台有活动部件的机器都有轮子，然而没有人知道第一个轮子究竟是什么时候发明的或者当时是作什么用途的。
分析：本句的主干是every machine has wheels 。
When 和what 位于knows 之后引导两个并列的宾语从句；with moving parts 为介词短语作定语修饰machine 。
2. Evidence suggests that wheels for transport didn’t become popular for a while, though.翻译：证据表明，不过当时轮子用于运输并没有普及。
分析：本句的主干是Evidence suggests that 。
That 引导宾语从句，此处suggest 意为“暗示、表明”，从句中用陈述语气。
句末though 是副词，意为“不过、然而”。
3. While wheels need to roll on smooth surfaces, roads with smooth surfaces weren’t going to be constructed until there was plenty of demand for them.译：尽管轮子需要在平滑的表面上滚动，但是有着光滑路面的道路并没有铺设直到后来对此需求越来越多。
分析：本句的主干是roads weren’t going to be constructed 。