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托福阅读词汇题:meager&rich

2015-08-25 10:57:15来源:网络

  【托福阅读词汇题:meager&rich新托福TPO阅读中,词汇题是重要托福阅读题型。托福阅读词汇题做题需要考生掌握一定的词汇量和做题技巧。本文中新东方在线托福网汇总了新托福阅读词汇150题:meager&rich

  Paragraph 5: The Jovian planets have very thick atmospheres consisting of varying amounts of hydrogen, helium, methane, and ammonia. By comparison, the terrestrial planets have meager atmospheres at best. A planet's ability to retain an atmosphere depends on its temperature and mass. Simply stated, a gas molecule can "evaporate" from a planet if it reaches a speed known as the escape velocity. For Earth, this velocity is 11 kilometers per second. Any material, including a rocket, must reach this speed before it can leave Earth and go into space. The Jovian planets, because of their greater masses and thus higher surface gravities, have higher escape velocities (21-60 kilometers per second) than the terrestrial planets. Consequently, it is more difficult for gases to "evaporate" from them. Also, because the molecular motion of a gas depends on temperature, at the low temperatures of the Jovian planets even the lightest gases are unlikely to acquire the speed needed to escape. On the other hand, a comparatively warm body with a small surface gravity, like Earth's moon, is unable to hold even the heaviest gas and thus lacks an atmosphere. The slightly larger terrestrial planets Earth, Venus, and Mars retain some heavy gases like carbon dioxide, but even their atmospheres make up only an infinitesimally small portion of their total mass. 【TPO16- Planets in Our Solar System】

  5. The word meager in the passage is closest in meaning to

  ○rich

  ○thin

  ○unique

  ○complex

  答案见下一页:

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