编辑点评: 研习GRE作文考试的优秀范文不仅可以学到有用的词汇和句子,更能从中学习逻辑的构建方式和作文框架的结构等内容,这里为大家提供GRE的范文,希望对同学们的备考有所帮助。
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. 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 in diameter. Thus if you enlarged a rounded bacterium a thousand times, it would be just about the size of a pinhead. An adult human magnified by the same amount would be over a mile tall.
Even with an ordinary microscope, you must look closely to see bacteria. Using a magnification of 100 times, one finds that bacteria are barely visible as tiny rods or dots. One cannot make out anything of their structure. Using special stains, one can see that some bacteria have attached to them wavy-looking hairs called flagella. Others have only one flagellum. The flagella rotate, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can glide along over surfaces by some little- understood mechanism.
From the bacteria point of view, the world is a very different place from what it is to humans. To a bacterium water is as thick as molasses is to us. Bacteria are so small that they are influenced by the movements of the chemical molecules around them. Bacteria under the microscope, even those with no flagella, often bounce about in the water. This is because they collide with the watery molecules and are pushed this way and that. Molecules move so rapidly that within a tenth of a second the molecules round a bacteria have all been replaced by new ones; even bacteria without flagella are thus constantly exposed to a changing environment.
SAT作文实例讲评
SAT写作素材:2014诺贝尔文学奖
SAT作文中间段修改实例讲解(二)
2014年10月9日SAT写作参考范文一
SAT作文满分经验分享
2014年10月9日SAT作文真题 含点评
九步修改你的SAT作文
SAT作文使用最多的100个词语搭配 上
SAT作文高分突破秘诀
写作技巧分享:Writing Tips from Oakley Hall
SAT作文五段式方法
SAT写作范文 含评分标准
SAT作文题目大全 55-60
SAT写作题目总结35-40
SAT考试作文范文一篇
揭开SAT写作的真实面目
SAT写作参考范文 Consciousness and Avarice
SAT写作法则及实例:在文章中使用借词
2014年10月SAT考试真题之写作范文
SAT写作素材Personal life
名词化在SAT写作中的用途
SAT写作的几个要点 from CB
SAT写作备考经验
SAT作文高分经验分享
SAT作文范文一篇
SAT作文名言名句
100个SAT热点词汇
SAT写作题目大全 81-86
SAT高分作文的特点
SAT写作:为你的论文写出一段简介(introduction)
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |