2. 考研
  3. Air is (1)_____, and like all matter, it has weight. Weight is the measure of the (2)_____ of gravity (3)_____ matter. If a scal

Air is (1)_____, and like all matter, it has weight. Weight is the measure of the (2)_____ of gravity (3)_____ matter. If a scal

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问题     Air is (1)_____, and like all matter, it has weight. Weight is the measure of the (2)_____ of gravity (3)_____ matter. If a scale registers 10 kilograms when a stone is placed on it, this means that gravity pulls the stone with that (4)_____ force. (5)_____, earth’s gravity pulls on each (6)_____ of gas and dust on the atmosphere. Because our atmosphere is a. vast (7)_____ of air, it has (8)_____. If it could (9)_____ be compressed and put on a (10)_____ of scales, it would weigh about 5,700,000,000,000,000 (quadrillion) metric tons.
    The air pressed down on us and against us (11)_____ all sides. Something (12)_____ a ton of air is pressing against you at this moment. You are not (13)_____ of this because air pressure within your body (14)_____ the pressure of the air outside.
    Air pressure is 1.036 kilograms per square centimeter (14.7 pounds per square inch) at sea (15)_____. It is greatest there because that is the (16)_____ of the atmosphere. (17)_____ higher altitudes the pressure is (18)_____. That is why the (19)_____ of highflying planes are pressurized. They are designed to (20)_____ the air pressure our bodies must have.

选项 A、produce
B、provide
C、maintain
D、improve
答案C
解析 本题是一道词义辨析题。produce的含义为"制造，生产"；provide的含义的"提供"；maintain的含义为"保持，维持"；improve的含义为"增加"。根据上下文意，此处选maintain最合适。
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考研英语一

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