费费宝典第39题

assfgrtrtr

39. Quasars---celestial objects so far away that their light takes at least 500 million years to reach Earth---have been seen since 1963. For anything that far away to appear from Earth the way quasars do, it would have to burn steadily at a rate that produces more light than 90 billion suns would produce. But nothing that burns at a rate that produces that much light could exist for more than about 100 million years. If the statements above are true, which one of the following must also be true on the basis of them? (A) Instruments in use before 1963 were not sensitive enough to permit quasars to be seen. (B) Light from quasars first began reaching Earth in 1963. (C) Anything that from Earth appears as bright as a quasar does must produce more light than would be produced by 90 billion suns. (D) Nothing that is as far from Earth as quasars are can continue to exist for more than about 100 million years. (E) No quasar that has ever been seen from Earth exists any longer. 答案是E,它是指比什么长(exists any longer than what?),死活想不通，C不对吗？

himba

感觉这个题目和答案有矛盾，既然要走五百万年才能看到，而本身又只有一百万年的寿命，那1963年是怎么看到quasars的？

ppp1

呵呵，既然我们看到得是五百万年前得星星，而这种星星又最多只能存在一百万年 所以等到我们看到它得时候，它肯定已经是烧光咯，就没有了咯 也就是我们看到得实际上已经是不存在得咚咚了