2. 自考
  3. When we accept the evidence of our unaided eyes and describe the Sun as a yellow star, we have summed up the most important sing

When we accept the evidence of our unaided eyes and describe the Sun as a yellow star, we have summed up the most important sing

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问题     When we accept the evidence of our unaided eyes and describe the Sun as a yellow star, we have summed up the most important single fact about it at this moment in time. It appears probable, however, that sunlight will be the color we know for only a negligibly small part of the Sun’s history.
    Stars, like individuals, age and change. As we look out into space, we see around us stars at all stages of evolution. There are faint bloodred dwarfs so cool that their surface temperature is a mere 4,000 degrees Fahrenheit, there are searing ghosts blazing at 100,000 degrees Fahrenheit and almost too hot to be seen, for the great part of their radiation is in the invisible ultraviolet range. Obviously, the "daylight" produced by any star depends on its temperature; today (and for ages to come) our Sun is at about 10,000 degrees Fahrenheit, and this means that most of the Sun’s light is concentrated in the yellow band of the spectrum, falling slowly in intensity toward both the longer and shorter light waves.
    That yellow "hump" will shift as the Sun evolves, and the light of day will change accordingly. It is natural to assume that as the Sun grows older, and uses up its hydrogen fuel—which it is now doing at the spanking rate of half a billion tons a second — it will become steadily colder and redder.
Why are very hot stars referred to as "ghosts"? (  )
选项 A、They are short lived.
B、They are mysterious.
C、They are frightening.
D、They are nearly invisible.
答案D
解析 推断题。“为什么很热的星星被称为‘鬼魂’?”D选项“因为它们几乎是不可视的”。文中说almost too hot to be seen，．．．in the invisible ultraviolet range，说明由于温度太高的缘故，这种放射线会不可见，所以被称为“鬼魂”。其他A选项“它们存在时间很短”；B选项“它们很神秘”；C选项“它们很吓人”。这几项与原文不符。
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