四级冲刺练习阅读90

　　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