[求助]11th OG 阅读115题

zgx_998

文中第一段说宇宙密度在达到每立方米3个氢原子的情况下就会停止膨胀，该题问如果密度明显小于每立方米3个氢原子时结果会怎样，答案选的是宇宙会继续无限地膨胀。

不知道出题人是怎么个逻辑。我的理解是，宇宙在膨胀时密度是逐步减小的，当减小到每立方米3个氢原子时就达到引力平衡不再膨胀，如果这样理解正确，那么当密度小于每立方米3个氢原子时，怎么可能又继续膨胀呢？

顾风

请参考：

http://forum.chasedream.com/dispbbs.asp?boardID=25&ID=87902&page=1

zgx_998

好像没有这篇哦

ecochem

这篇阅读好像是新的，OG10没有呀

我也跟楼主有一样的疑问，请NN帮忙解答！

caterpillarcn

can you post the whole passage? then we can have a full pic about it

喵喵猫

我的理解是:

第9行,有个强转折词but,就是说作者的重点放在转折后面,他要强调的也是转折后的内容,

可观察到的宇宙的密度在星系的发光物质中只占一小部分,后面又一个假设词If.....is to stop,也就是说他也还不确定,究竟会不会停止,如果会,那么在这个宇宙中就需要有足够的可以被见到的物质........

zgx_998

哦，我想明白了，以前学过天体物理学，把这个问题想复杂了^_^

其实只要通过句法分析就能得出答案。

第一段：After evidence was obtained in the 1920's that the universe is expanding, it became reasonable to ask: will the universe continue to expand indefinitely, or is there enough mass in it for the mutual attraction of its constituents to bring the expansion to a halt? It can be calculated that the critical density of matter needed to brake the expansion and "close" the universe is equivalent to three hydrogen atoms per cubic meter.
        But the density of the observable universe-luminous matter in the form of galaxies-comes to only a fraction of this.
        If the expansion of the universe is to stop, there must be enough invisible matter in the universe to exceed the luminous matter in density by a factor of roughly 70.

115题：It can be inferred from information presented in the passage that if the density of the universe were equivalent ro  significantly less than three hydrogen atoms per cubic meter, which of the following would be ture as a consequence?

(A) Luminosity would be a true indicator of mass.

(B) Different regions in spiral galaxies would rotate at the same velocity.

(C) The universe would continue to expand indefinitely.

(D) The density of the invisible matter in the universe would have to be more than 70 times the density of the luminous matter.

(E) More of the invisible matter in spiral galaxies would have to be located in their nuclei than in their outer regions.

答案选(C) 

我的理解：红句说宇宙停止膨胀的密度是3个氢原子每立方米；蓝句说能观察到的光物质的密度只是这一个值的一小部分；绿句说如果宇宙现在停止膨胀，那么宇宙中暗物质的密度就要比光物质的密度大70倍（exceed...by a factor of...  的意思不知把握对不对？），也就是说，暗物质和光物质的总密度要等于3个氢原子每立方米。如果事实上宇宙中暗物质的质量并没有设想的那么大，那么暗物质和光物质的总密度就会小于3个氢原子每立方米，也即是115题问的那种情况。然后不要再往下想物理学的东西了，再看一遍绿句的因果关系：如果宇宙要停止膨胀，那么就要有足够多的暗物质。取非，如果没有那么多暗物质，宇宙就会继续膨胀。

从这一题能体会到，做阅读题的时候千万不要把出题人想得太高深，他们往往不是通过具体知识，而是通过文章的句法结构来出题的。

starist

以下是引用zgx_998在2006-9-4 1:46:00的发言：

哦，我想明白了，以前学过天体物理学，把这个问题想复杂了^_^

其实只要通过句法分析就能得出答案。

第一段：After evidence was obtained in the 1920's that the universe is expanding, it became reasonable to ask: will the universe continue to expand indefinitely, or is there enough mass in it for the mutual attraction of its constituents to bring the expansion to a halt? It can be calculated that the critical density of matter needed to brake the expansion and "close" the universe is equivalent to three hydrogen atoms per cubic meter.
  But the density of the observable universe-luminous matter in the form of galaxies-comes to only a fraction of this.
  If the expansion of the universe is to stop, there must be enough invisible matter in the universe to exceed the luminous matter in density by a factor of roughly 70.

115题：It can be inferred from information presented in the passage that if the density of the universe were equivalent ro  significantly less than three hydrogen atoms per cubic meter, which of the following would be ture as a consequence?

(A) Luminosity would be a true indicator of mass.

(B) Different regions in spiral galaxies would rotate at the same velocity.

(C) The universe would continue to expand indefinitely.

(D) The density of the invisible matter in the universe would have to be more than 70 times the density of the luminous matter.

(E) More of the invisible matter in spiral galaxies would have to be located in their nuclei than in their outer regions.

答案选(C) 

我的理解：红句说宇宙停止膨胀的密度是3个氢原子每立方米；蓝句说能观察到的光物质的密度只是这一个值的一小部分；绿句说如果宇宙现在停止膨胀，那么宇宙中暗物质的密度就要比光物质的密度大70倍（exceed...by a factor of...  的意思不知把握对不对？），也就是说，暗物质和光物质的总密度要等于3个氢原子每立方米。如果事实上宇宙中暗物质的质量并没有设想的那么大，那么暗物质和光物质的总密度就会小于3个氢原子每立方米，也即是115题问的那种情况。然后不要再往下想物理学的东西了，再看一遍绿句的因果关系：如果宇宙要停止膨胀，那么就要有足够多的暗物质。取非，如果没有那么多暗物质，宇宙就会继续膨胀。

从这一题能体会到，做阅读题的时候千万不要把出题人想得太高深，他们往往不是通过具体知识，而是通过文章的句法结构来出题的。

这题我也晕，觉得应该选A或者D，

因为根据lz上面的分析，红句到绿句的逻辑范式为

1.前提1：critical density of matter needed to brake the expansion or a "close" ＝3 (单位/空间)

2.前提2：光物质不到这个密度；

3.前提3：expansion of the universe is to stop（停止扩张）

4.假定1(我自己理解的)：继续扩张所需密度比已停止扩张密度要大。

5.结论：存在暗物质，且暗物质密度为光物质70倍。

以上1+2+3+4，推到 5。

题干的意思为1，不变; 2被部分加强(宇宙不到这个密度——光物质更不到这个密度)2; 3不知道。

那么我觉得可以推出如果3为已经停止扩张，则就是D暗物质更多。（似乎有点勉强）

但是如果推出C，更有点无厘头，求大牛解。。。

starist

今晚回家的班车上仔细推敲终于出来了，

题目要求根据文章内容：

1.第一段，现在的情况是
a.evidence was obtained in the 1920's that the universe is expanding(即宇宙确实在膨胀)
b.宇宙的膨胀的门限值为密度＝3

所以，推论为现在宇宙的情况为密度大于或者等于3，比如4,(膨胀的概念就是体积由小到大，常识前提质量不变的化，密度就是由大到小)

2.最后一段，说明门限为3还是又问题的，可能被推翻。

那么题目告诉我们假设宇宙的密度走到了小于3，比如2

请注意，
前提1(原文)：推论为现在宇宙的情况为密度大于或者等于3
前提2(题目)：宇宙的密度走到了小于3

结论很清楚：从大于等于3（比如4）走到小于3（比如2），代表密度变小，宇宙继续膨胀。

最后一段为defender：告诉我们门限3实际上不一定存在，不管它。

——我复习后觉得为OG11阅读终极boss题！！！

Friskies

以下是引用zgx_998在2006-9-4 1:46:00的发言：

哦，我想明白了，以前学过天体物理学，把这个问题想复杂了^_^

其实只要通过句法分析就能得出答案。

第一段：After evidence was obtained in the 1920's that the universe is expanding, it became reasonable to ask: will the universe continue to expand indefinitely, or is there enough mass in it for the mutual attraction of its constituents to bring the expansion to a halt? It can be calculated that the critical density of matter needed to brake the expansion and "close" the universe is equivalent to three hydrogen atoms per cubic meter.
  But the density of the observable universe-luminous matter in the form of galaxies-comes to only a fraction of this.
  If the expansion of the universe is to stop, there must be enough invisible matter in the universe to exceed the luminous matter in density by a factor of roughly 70.

115题：It can be inferred from information presented in the passage that if the density of the universe were equivalent ro  significantly less than three hydrogen atoms per cubic meter, which of the following would be ture as a consequence?

(A) Luminosity would be a true indicator of mass.

(B) Different regions in spiral galaxies would rotate at the same velocity.

(C) The universe would continue to expand indefinitely.

(D) The density of the invisible matter in the universe would have to be more than 70 times the density of the luminous matter.

(E) More of the invisible matter in spiral galaxies would have to be located in their nuclei than in their outer regions.

答案选(C) 

我的理解：红句说宇宙停止膨胀的密度是3个氢原子每立方米；蓝句说能观察到的光物质的密度只是这一个值的一小部分；绿句说如果宇宙现在停止膨胀，那么宇宙中暗物质的密度就要比光物质的密度大70倍（exceed...by a factor of...  的意思不知把握对不对？），也就是说，暗物质和光物质的总密度要等于3个氢原子每立方米。如果事实上宇宙中暗物质的质量并没有设想的那么大，那么暗物质和光物质的总密度就会小于3个氢原子每立方米，也即是115题问的那种情况。然后不要再往下想物理学的东西了，再看一遍绿句的因果关系：如果宇宙要停止膨胀，那么就要有足够多的暗物质。取非，如果没有那么多暗物质，宇宙就会继续膨胀。

从这一题能体会到，做阅读题的时候千万不要把出题人想得太高深，他们往往不是通过具体知识，而是通过文章的句法结构来出题的。

你分析的很有道理啊。我原来看过之后也晕了，但是做题的关键就是不能掺入任何主观色彩，文章说啥就信啥，他不说你就什么都不知道，就容易理解了。