The difference between a liquid and a gas is obvious under the conditions of temperature and pressure commonly found at the surface of the Earth. A liquid can be kept in an open container and fill it to the level of a free surface. A gas forms no free surface but tends to diffuse throughout the 11 available; it must therefore be kept in a closed container or held by a gravitational field, as in the 12 of a planets atmosphere. The distinction was a 13 feature of early theories describing the phases of matter. In the nineteenth century, for example, one theory maintained that a liquid could be dissolved in a vapor without losing its identity, and another theory 14 that the two phases are made up of different kinds of molecules. The theories now prevailing take a quite different approach by emphasizing what liquids and gases have in 15 They are both forms of matter that have no 16 structure, and they both flow readily. The fundamental similarity of liquids and gases becomes clearly apparent when the temperature and pressure are 17 somewhat. Suppose a closed container 18 filled with a liquid is heated. The liquid expands, or in other words becomes less dense; some of it evaporates. In contrast, the vapor above the liquid surface becomes denser as the evaporated molecules are 19 to it. The combination of temperature and pressure at which the densities become 20is called the critical point. A. added B. case C. prominent D. held E. equal F. partially G. example H. previous I. space J, lifted K. permanent L. particularlyM. extended N. raised 0. common II. I 12. B 13. C 14. D 15. O 16. K 17. N 18. F 19. A 20. E
第1课 打电话预约医生-3
第1课 打电话之服务电话 - 1
那些“表里不一”的英语口语用法
一个人也能练习流利口语
第1课 打电话之日常通话 - 11
【口语预测】2010年最有可能考到的十道题
第1课 打电话之日常通话 - 5
十句简单英语提升口语档次
BEC商务英语口语词汇详解(21)
第1课 打电话之商业电话 - 1
第1课 取消服务-2
口语Topic 练习
第1课 打电话之日常通话 - 10
第1课 服务电话 - 11
第1课 打紧急电话-4
【口语天天向上】轻松每日一说(1)
【双语】提高英语口语的11秘籍
第1课 打电话之服务电话 - 2
第1课 打电话之服务电话 - 6
第1课 服务电话 - 8
2010年1月雅思口语考题预测
第1课 打电话预约医生-4
第1课 打紧急电话-1
第1课 服务电话 - 9
不能止步不前
别放心上哈
第1课 叫出租车-2
爷爷叫你放轻松
第1课 商业电话-6
小诀窍练就完美英语发音
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |