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  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

admin2011-01-14  83
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 (微不足道的) 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 blooded dwarfs so cool that their surface temperature is a mere 4,000 degrees Fahrenheit; there are scaring ghosts blazing at 100,000 degrees Fahrenheit and almost too hot to be seen, for the great part of their radia-tion 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 de-grees 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 the 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 sec-ond-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 本题属细节判断题。在第二段的第二句讲到：有令人恐怖的幽灵星球的温度高达100000华氏度，几乎热得让人看不见；称呼这些星球为幽灵是因为它们难以见到，与人们想象中的不可见的鬼有相似之处。too…to是表否定的句型，与D项中的invisible“看不见”意思是一致的，故选D。
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