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大學(xué)英語六級考試閱讀單項(xiàng)題沖關(guān)練習(xí)

　　if you find a path with no obstacles, it probably doesn’t lead anywhere.以下是小編為大家搜索整理的大學(xué)英語六級考試閱讀單項(xiàng)題沖關(guān)練習(xí)，希望能給大家?guī)韼椭?更多精彩內(nèi)容請及時關(guān)注我們應(yīng)屆畢業(yè)生考試網(wǎng)!

大學(xué)英語六級考試閱讀單項(xiàng)題沖關(guān)練習(xí)

　　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 planet's 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 20 is 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. particularly