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OFFICIAL51 According to paragraph 3, Earth's surface is different from the surfaces of many other planetary bodies in which of the following ways?

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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.

9.According to paragraph 3, Earth's surface is different from the surfaces of many other planetary bodies in which of the following ways?

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【题目翻译】根据第3段,地球表面与许多其他行星体的表面有以下哪种不同? A:它以河谷和侵蚀为特征。 B:地质活动性更强。 C:它被撞击坑所覆盖。 D:有大气。 【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“other planetary bodies”可以直接定位到这一句“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.”原句意思是:结果,地球表面不断发生变化,侵蚀成细微的河谷系统,这与撞击坑占主导地位的其他行星体的表面形成了显著的对比。 【逻辑分析】根据段落和定位句,可以知道地球与其他星球的不同之处在于,地球的表面不断地发生变化,受到侵蚀,形成复杂的河谷系统。 A选项:它以河谷和侵蚀为特征。与原文意思相符,正确。 B选项:地球的地理活跃度更高。第三段只提到地球的地理活跃度高,但没有说它比其它星球地理活跃度更高。故比较关系不存在,B排除。 C选项:地球表面被陨石坑覆盖。错误,因为文中说的是其他星球表面布满陨石坑。故C选项与原文信息矛盾。C选项错误。 D选项:地球有大气。但根据前文内容我们知道,金星也有大气。所以这不是地球独一无二,能够将其与其他星球区分开的特征。故D选项排除。

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