英语六级阅读模拟练习和答案

　　下面是学习啦小编整理的英语六级阅读模拟练习和答案，希望对大家有帮助。

　　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

　　M. 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


 

　　Scientists at Sussex University appear to be on the way to 11 how the mosquito, carrier of diseases such as malaria and yellow fever, homes in on its target. The problem is that they have found that the best way to avoid being bitten is: stop breathing, stop sweating, and keep down the temperature of your immediate surroundings. 12 the first suggestion is impossible and the others very difficult.

　　Scientists have found that there are three 13 stages in a mosquito's assault. Stage one is at fifty feet away, when the insect first smells a man or a animal to 14 . Stage two is thought to come into operation about twenty-five feet from the target, when the insect becomes guided by the carbon dioxide breathed out by the intended victim. Stage three is when the mosquito is only a matter of inches from its 15 the warmth and moisture given off by the victim is the final clue.

　　The researchers then * 16 how repellents interfere with its three-stage attack. They found repellents act more subtly than by just giving off a nasty smell. A Canadian researcher says that repellents appear to 17 mosquitoes first when it is following the carbon dioxide and second during the final approach, where the warmth and moisture are the insect's 18 .

　　Air pervaded by one of the many chemical repellents stops the mosquito reacting to the victim's carbon dioxide, and the repellent seems to affect the tiny hairs with which the insect senses moisture in the air. The sensors are blocked so that the 19 does not know whether it is flying through a moist current, or

　　the sensors are made to send the 20 signals.

　　A. examined

　　B. animal

　　C. wrong

　　D. insect

　　E. bite

　　F. Unfortunately

　　G. inventing

　　H. distinct

　　I. prey

　　J. guide

　　K. checked

　　L. definite

　　M. Unnecessarily

　　N. confuse

　　O. discovering


 

　　11. O 12. F 13. H 14. E 15. I 16. A 17. N 18. J 19. D 20. C