The difference between a liquid and a gas is obvious 67 the conditions of temperature and pressure 68 found at the surface of the Earth. A liquid can be kept in an open container and fills it to the level of a free surface. A gas forms no free surface but 69 to diffuse through- out the space available; it must- 70 be kept in a. closed container, as in the 71 of a planet's atmosphere. The distinction was a prominent feature of early theories 72 the phases of matter. In the nineteenth century, for example, one theory 73 that a liquid could be "dissolved" in a vapor without losing its identity, and 74 theory held that the two phases are made up of different kinds of molecules (分子). The theories now prevailing 75 a quite different approach by emphasizing 76 liquids and gases have in common. They are both forms of matter that have no permanent structure, 77 they both flow easily. They are fluids. The 78 similarity of liquids and gases becomes clearly apparent when the temperature and pressure are raised somewhat. 79 a closed container partially filled with a liquid is heated. The liquid expands or in other 80 , becomes less dense; some of it evaporates. In 81 , the vapor above the liquid surface becomes denser as the evaporated molecules are added 82 it. The combination of temperature and pressure at. 83 the densities become equal is 84 the critical point. Above the critical point the liquid and the gas can no longer be 85 ; there is a single, undifferentiated fluid phase of 86 density.
67. A．in
B．on考試大－全國教育類網(wǎng)站(www．Examda。com)
C．under
D．beyond
68. A．commonly
B．quickly
C. speedily
D broadly
69. A．intends
B．tends
C．inclines
D．contends
70. A．however
B. nevertheless
C．so
D. therefore
71. A．event
B case
C. interest
D．face考試大論壇
72. A I presenting
B．submitting
C．describing
D．painting
73. A．maintained
B．verified
C．prescribed
D．displayed
74. A．a(chǎn)nother
B．other
C one
D．else
75. A．a(chǎn)pply
B．a(chǎn)dapt
C take
D．conduct
76. A why
B．what
C how
D．that
77. A and
B．so
C．but
D．or
78. A comparative
B．crucial
C insignificant
D fundamental
79. A Suppose
B．Prove
C 3 Mean
D Relate
80. A．means
B．ways
C words
D．cases
81. A proportion
B contrast
C response
D reply
82. A to
B on
C up
D in
83. A this
B that
E C whose
D which
84. A known來源：www.examda.com
B defined
C．called
D referred
85. A classified
B recognized
C categorized
D distinguished
86. A．inevitable
B consistent
C uniform
D persistent
【結(jié)構(gòu)剖析】說明文。本文主要介紹了液體和氣體的不同點(diǎn)和相似點(diǎn)。首先提到液體和氣體的區(qū)別在通常情況是很明顯的，隨后提到當(dāng)溫度和氣壓升高時(shí)二者的相似性就變得十分明顯。
67. A．in
B．on考試大－全國教育類網(wǎng)站(www．Examda。com)
C．under
D．beyond
68. A．commonly
B．quickly
C. speedily
D broadly
69. A．intends
B．tends
C．inclines
D．contends
70. A．however
B. nevertheless
C．so
D. therefore
71. A．event
B case
C. interest
D．face考試大論壇
72. A I presenting
B．submitting
C．describing
D．painting
73. A．maintained
B．verified
C．prescribed
D．displayed
74. A．a(chǎn)nother
B．other
C one
D．else
75. A．a(chǎn)pply
B．a(chǎn)dapt
C take
D．conduct
76. A why
B．what
C how
D．that
77. A and
B．so
C．but
D．or
78. A comparative
B．crucial
C insignificant
D fundamental
79. A Suppose
B．Prove
C 3 Mean
D Relate
80. A．means
B．ways
C words
D．cases
81. A proportion
B contrast
C response
D reply
82. A to
B on
C up
D in
83. A this
B that
E C whose
D which
84. A known來源：www.examda.com
B defined
C．called
D referred
85. A classified
B recognized
C categorized
D distinguished
86. A．inevitable
B consistent
C uniform
D persistent
【結(jié)構(gòu)剖析】說明文。本文主要介紹了液體和氣體的不同點(diǎn)和相似點(diǎn)。首先提到液體和氣體的區(qū)別在通常情況是很明顯的，隨后提到當(dāng)溫度和氣壓升高時(shí)二者的相似性就變得十分明顯。