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OFFICIAL51 According to paragraph 3, why is water able to move so freely on Earth?

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Surface Fluids on Venus and Earth
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A fluid is a substance, such as a liquid or gas, in which the component particles (usually molecules) can move past one another. Fluids flow easily and conform to the shape of their containers. The geologic processes related to the movement of fluids on a planet's surface can completely resurface a planet many times. These processes derive their energy from the Sun and the gravitational forces of the planet itself. As these fluids interact with surface materials, they move particles about or react chemically with them to modify or produce materials. On a solid planet with a hydrosphere and an atmosphere, only a tiny fraction of the planetary mass flows as surface fluids. Yet the movements of these fluids can drastically alter a planet. Consider Venus and Earth, both terrestrial planets with atmospheres.

Venus and Earth are commonly regarded as twin planets but not identical twins. They are about the same size, are composed of roughly the same mix of materials, and may have been comparably endowed at their beginning with carbon dioxide and water. However, the twins evolved differently largely because of differences in their distance from the Sun. With a significant amount of internal heat, Venus may continue to be geologically active with volcanoes, rifting, and folding. However, it lacks any sign of a hydrologic system (water circulation and distribution): there are no streams, lakes oceans or glaciers. Space probes suggest that Venus may have started with as much water as Earth, but it was unable to keep its water in liquid form. Because Venus receives more heat from the Sun, water released from the interior evaporated and rose to the upper atmosphere where the Sun's ultraviolet rays broke the molecules apart. Much of the freed hydrogen escaped into space, and Venus lost its water. Without water, Venus became less and less like Earth and kept an atmosphere filled with carbon dioxide. The carbon dioxide acts as a blanket, creating an intense greenhouse effect and driving surface temperatures high enough to melt lead and to prohibit the formation of carbonate minerals. Volcanoes continually vented more carbon dioxide into the atmosphere. On Earth, liquid water removes carbon dioxide from the atmosphere and combines it with calcium, from rock weathering, to form carbonate sedimentary rocks. Without liquid water to remove carbon from the atmosphere, the level of carbon dioxide in the atmosphere of Venus remains high.

Like Venus, Earth is large enough to be geologically active and for its gravitational field to hold an atmosphere. Unlike Venus, it is just the right distance from the Sun so that temperature ranges allow water to exist as a liquid, a solid, and a gas. Water is thus extremely mobile and moves rapidly over the planet in a continuous hydrologic cycle. Heated by the Sun, the water moves in great cycles from the oceans to the atmosphere, over the landscape in river systems, and ultimately back to the oceans. As a result, Earth's surface has been continually changed and eroded into delicate systems of river valleys - a remarkable contrast to the surfaces of other planetary bodies where impact craters dominate. Few areas on Earth have been untouched by flowing water. As a result, river valleys are the dominant feature of its landscape. Similarly, wind action has scoured fine particles away from large areas, depositing them elsewhere as vast sand seas dominated by dunes or in sheets of loess (fine-grained soil deposits). These fluid movements are caused by gravity flow systems energized by heat from the Sun. Other geologic changes occur when the gases in the atmosphere or water react with rocks at the surface to form new chemical compounds with different properties. An important example of this process was the removal of most of Earths carbon dioxide from its atmosphere to form carbonate rocks. However, if Earth were a little closer to the Sun, its oceans would evaporate; if it were farther from the Sun, the oceans would freeze solid. Because liquid water was present, self-replicating molecules of carbon, hydrogen, and oxygen developed life early in Earth's history and have radically modified its surface, blanketing huge parts of the continents with greenery. Life thrives on this planet, and it helped create the planet's oxygen- and nitrogen-rich atmosphere and moderate temperatures.

10.According to paragraph 3, why is water able to move so freely on Earth?

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正确答案:A
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【题目翻译】根据第3段,为什么水能在地球上如此自由地移动? A:地球的温度使得水以固体、液体和气体形式存在。 B:地球足够大,地质活动性强,其重力场可以容纳大气。 C:地球表面允许河流峡谷横跨地形发展。 D:地球有活跃的风吹过海洋引起流体运动。 【判定题型】:题目问的是文章中的具体细节信息,故根据题目问法可以判断本题为事实信息题。 【关键词定位】根据题干中的关键词“water”和“move”,可以定位到第三段第2、3句“Unlike Venus, it is just the right distance from the Sun so that temperature ranges allow water to exist as a liquid, a solid, and a gas. Water is thus extremely mobile and moves rapidly over the planet in a continuous hydrologic cycle.”意思是:不像金星,它离太阳的距离恰到好处,所以温度范围允许水以液体、固体和气体的形式存在。因此,水极其移动,并以连续的水文循环在地球上快速移动。 【逻辑分析】第2句说地球适宜的温度范围能够使水以液体、固体和气体的形式存在。特别需要注意第3句中“thus”这个词,能体现明显的因果关系,所以地球上水能自由流动的原因,就是前面的第2句话。 【选项分析】 A选项:地球的温度使得水以固体、液体和气体形式存在。正确。 B选项:地球很大、地质活动活跃、引力能维持大气。这是地球与金星的共同点,不是水能流动的原因,属于无关干扰信息,排除。 C选项:地球表面使河谷能够穿过。根据文意我们知道,是地球上的水造就了河谷的地貌,而C选项逻辑颠倒,将结果作为原因,故C选项排除。 D选项:地球的风力作用在吹过海洋时会造成流体运动。错误,因为文中只提到风力作用会带动细颗粒运动,形成沙漠。故D选项为无中生有,排除。

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