[求助]feifei-39

perillayue

我觉得这道题解释不是说题干没有定义，是说C选项没有定义anything与地球的距离，也就是说如果所提到的ANYTHING 距离地球比 Quasars近的话，就不会需要产生那么多能量了

Jolie881209

Answer choice (C) is really close and in fact would be correct if it read, "Anything as far away as a quasar and as bright as a quasar must produce more light than would be produced by 90 billion suns."

The problem is that the stimulus qualifies the statement with information about the object being as far away as quasars, whereas answer choice (C) does not.

Theoretically, a quasar so far away would appear very faint. So an object that was closer, would not necessarily need to be so bright as 90 billion billion suns worth of light. For example, the moon might be brighter and be produced with less light, because it is so near in our sky.

Does that help clear things up?

Jolie881209

不好意思~ 帖子没贴齐~



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?

If the statements above are true, which one of the following must also be true on the basis of them?

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：E



思路：



A：可能足够sensative，只是没有观察到而已。



B：同样只是没有观察到而已。



C：没有定义与地球的距离。



D：没有定义亮度



E：原文实际认为现在看到的来自Quasars的光是500万年前发出的。而在400万年前这些类星体就已经燃尽不存在了。







Choice C 里, 解释说题干没定义, 但我看题干有叙述到.
     



不知是否有哪位大大知道 choice C 错的原因为何?
   

[此贴子已经被作者于2006-8-13 12:50:49编辑过]

-- by 会员 swenet2000 (2006/8/13 12:46:00)

Answer choice (C) is really close and in fact would be correct if it read, "Anything as far away as a quasar and as bright as a quasar must produce more light than would be produced by 90 billion suns."

The problem is that the stimulus qualifies the statement with information about the object being as far away as quasars, whereas answer choice (C) does not.

Theoretically, a quasar so far away would appear very faint. So an object that was closer, would not necessarily need to be so bright as 90 billion billion suns worth of light. For example, the moon might be brighter and be produced with less light, because it is so near in our sky.

Does that help clear things up?

emmayuan

不明白,如果400万年前就消失了,离地球有500M那么远,那1963年那次是怎么看到的阿....我凌乱了