Bacteria(细菌) are extremely small living things. While we measure our own sizes

题文

Bacteria(细菌) are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in micron. One micron is a thousandth of a millimeter; a pinhead is about a millimeter across, Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron across. Thus, if you magnified a rounded bacterium a thousand times, it would be just the size of a pinhead, while a grown-up human enlarged by the same amount would be over a mile tall. Even with an ordinary microscope(显微镜), you must look cloly to e bacteria. Using a magnification of 100 times, one can hardly find bacteria. Nor can one make out anything of their structure(结构), of cour. only by using special colors, can one e that some bacteria have wavy-looking “hairs” called flagella. Others have only one flagellum. The flagella move round a central point, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can move along over surface by some little-understood “machinery”. From the bacterial point of view, the world is a very different place from what it is to humans. To a bacterium, water is as thick as molass(糖浆) is to us. Bacteria are so small that they are affected by the movements of the chemical molecules(分子) around them. Bacteria under microscopes, even tho with no flagella, often jump up and down in the water. This is becau they knock with the water molecules and are pushed this way and that.36. The underlined word magnified means _______________.A. enlarged  B. widened  C. killed  D. caught37. We know from the passage that _______________ is the smallest.A. a pinhead    B. a rounded bacterium C. a microscope    D. a rod-shaped bacterium38. The relationship between a bacterium and its flagella is most nearly like which of the following?A. A rider jumping on a hor back B. A ball being hit by a betC. A boat powered by a motorD. A door clod by wind39. Why does the writer compares water to molass in the third paragraph? A. To tell us how difficult it is for bacteria to move through water. B. To suggest that bacteria are fond of different liquids. C. To show different chemicals are of different structures. D. To show that bacteria are the best swimmers.40. Which of the following is the main topic of the passage?A. The characteristic (特点) of bacteria.  B. How bacteria reproduce.C. The various parts of a bacterium’s bodyD. How bacteria cau dias. 题型：未知难度：其他题型

答案

小题1:A小题2:B小题3:C小题4:A小题5:A

解析

略

考点

据考高分专家说，试题“ Bacteria(细菌) are ex.....”主要考查你对 [健康环保类阅读 ]考点的理解。 健康环保类阅读

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健康环保类文章常是介绍科学知识、生活常识和环境保护方面的短文。体裁有记叙文、 说明文、议论文和各种应用文。

健康环保类文章阅读技巧：

   健康环保类文章常是介绍科学知识、生活常识和环境保护方面的短文。阅读此类短文要以现象或事物为中心进行思考，理解现象产生的原因、条件和客观规律等。同时要抓住事物的特征、用途和相互关系等。科普环保类文章一般为说明文，从结构上看大致可分为三个部分：   第一部分一般是文章的首段，主要用来提出文章的主题，即文章想要阐述、说明的主要内容；   第二部分是文章的主体，可由若干个段落组成，对文章的主题进行展开说明；   第三部分是结尾段，对文章的主题进行归纳总结。这类文章多用一般现在时，而且一般多使用客观性词语表述。有时为了强调客观性，也常使用被动语态。   从近几年的考试题来看，科普环保类的文章越来越与人们的实际生活相接近。由于此类文章缺乏故事情节，很多同学对此类文章感到费解。但一般的科普类文章都是就事论事，需要逻辑推理和想象的时候较少，因此此类阅读题也没有同学们想象中的那么难，只要多加训练，就能较好地答题。【阅读策略】 1、概要(Summarizing)：  阅完材料后，将所阅材料浓缩，摘要，做出所阅材料的书面或口头梗概。 2、组织(Organization)：  阅读后根据阅读内容，识别观点、人物、事件之间的关系以及文章的结构关系。如：时间关系、比较或对比关系、相关关系及因果关系等。