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小站阅读41 是关于地球金星那一篇, 里面第三题:我觉得答案应该选A呀,答案给的是D。原文也附在下面。谢谢各位。
In fact, water probably once dominated the Venusian atmosphere. Venus and Earth are similar in size and mass, so Venusian volcanoes may well have outgassed as much water vapor as on Earth, and both planets would have had about the same number of comets strike their surfaces. Studies of how stars evolve suggest that the early Sun was only about 70 percent as luminous as it is now, so the temperature in Venus’ early atmosphere must have been quite a bit lower. Thus water vapor would have been able to liquefy and form oceans on Venus. But if water vapor and carbon dioxide were once so common in the atmospheres of both Earth and Venus, what became of Earth’s carbon dioxide? And what happened to the water on Venus?
3.According to paragraph 2, what is one reason for thinking that at one time, there were significant amounts of water on Venus?
A. Because of Venus’ size and mass, its volcanoes probably produced much more water vapor than volcanoes on Earth did. B. The low temperature of Venus' early atmosphere can be explained only by the presence of water. C. The presence of carbon dioxide in a planet's atmosphere is an indicator of water on that planet. D. Venus probably was struck by roughly as many comets as Earth was.
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