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问题 选择题

打开热水瓶盖，瓶口冒白雾，白雾上升一段距离后消失．与此有关的性质是（　　）

①水分子很小；②水分子不断运动；③水分子间有间隔；④水分子可以再分．

A．①②③

B．①②④

C．②③④

D．①②③④

答案

倒开水时，应将热水瓶塞放在桌面上，此时能够观察到瓶口出现白雾，白雾上升一段距离后消失，这是因为：①水分子很小用肉眼看不到；②水分子在不断运动；③水分子间的间隔增大变为水蒸气．这一过程属于物理变化，不能证明水分子可以再分，只有化学变化才能证明分子可以再分．

故选A．

听力题

第三部分写作（共三节，满分55分）   

单词拼写（共10小题，每小题1分，满分10分）

66. Who gave you___(允许)to leave the office so early?                                     66._______

67. The Japanese are used to___(鞠躬)to each other when they meet.                   67._______

68. Not long ago a___(猛烈的)earthquake occurred off the coast of Indonesia.     68._______

69. There is a lot of rubbish___(漂浮)on the surface of the river.                         69._______

70. He tried to flee across the___(边境)but was caught.                                      70._______

71. They started a___(运动)to stop people smoking.                                           71._______

72. Now people in the south grow a lot of rice that has a high__(产量).               72._______

73. As you ___(接近)the town, the first building you see is the church.           73._______

74. To my___(开心), the boy acted an old woman to sing a popular song.            74._______

75. You’d better___(咨询) a doctor about your illness.                                       75._______
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单项选择题

图10-18所示电路的等效电阻Rab应为下列选项中的（）Ω。

A.5

B.5.33

C.5.87

D.3.2
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