問題詳情

Questions 30-39The atmosphere of Venus is quite different from ours. Measurements taken from theEarth show a high concentration of carton dioxide in the atmosphere of Venus. In fact,carbon dioxide makes up 96 percent of Venus* atmosphere; nitrogen makes up almost allLine the rest. The Earth's atmosphere, by comparison, is mainly nitrogen, with a fair amount5 of oxygen as well. Carbon dioxide makes up less than 0.1 percent of the terrestrial atmosphere,The surface pressure of Venus* atmosphere is 90 limes higher than the pressure ofEarth's atmosphere, as a result of the large amount of carbon dioxide in the former.Throughout Earth's history, carbon dioxide on Earth has mixed with rain to dissolve10 rocks; the dissolved rock and carbon dioxide eventually flow into the oceans, where they precipitate to fonn new terrestrial rocks, often with the help of life-forms. If this carbondioside were released from the Earth's rocks, along with ower carton dioxide trapped inseawater, our atmosphere would become as dense and have as high a preasore as that ofVenus. Venus, slightly closer to the Sun than Earth and thus hotter, had no'oceans in15 which the carbon dioxide could dissolve or life to help take up the carbon.Also, Venus has probably lost almost all the water it ever had. Since Venus is closerto the Sun than the Earth is, its lower atmosphere was hotter even early on. The resultwas that more water vapor went into its upper atmosphere, where solar ultraviolet raysbroke in up into hydrogen and oxygen. The hydrogen, a light gas, escaped easily; the20 oxygen has combined with other gasses or with iron on Venus1 surface.Studies from the Earth show that the clouds on Venus are primarily composed of droplets of sulfuric acid, with water droplets mixed in* Sulfuric acid may sound strangeas a cloud constituent, but the Earth too has a significant layer of sulfuric acid dropletsin its stratosphere. However, the water in the lower layers of the Earth's atmosphere,25 circulating because of weather, washes the sulfur compounds out of these layers, whereas Venus has sulfur compounds in me lower layers of its atmosphere in addition to those inits clouds.
30. What does the passage mainly discuss?
(A) Atmospheric differences between Venus and Earth
(B) How Venus lost the water it once had
(C) The influence of the Sun on Venus
(D) A comparison between the upper and lower atmosphere on Venus

參考答案

答案：[無官方正解]
難度：非常困難0
統計：A(0),B(0),C(0),D(0),E(0)

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