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标题: 新prep-97 [打印本页]

作者: fengchen318    时间: 2011-5-25 16:30
标题: 新prep-97
It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite.However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets.So, even if bacteria did arrive on Earth from Mars, they must have died out.

The argument is most vulnerable to which of the following criticisms?

A. It fails to establish whether bacteria actually developed on Mars.

B. It fails to establish how likely it is that Martian bacteria were transported to Earth.

C. It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.

D. It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.

E. It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.

答案是D,能明白,但是始终不明白E为什么错。求解答,谢谢了~


作者: mudiduange    时间: 2011-5-25 17:01
文章的关键点:
  因为:  1、不同星球上的细菌具有显著的不同点;
             2、地球上的细菌没有发现这样的不同点。

  因此:即使地球上曾经有火星上的细菌,也已经死了。

  这个里面有个潜在的假设,就是这批细菌是地球上的细菌。这点是有错误,比如地球上现在的细菌都是从火星来的,地球原本没有细菌呢?

 E选项:
 是否有细菌来自于地球然后死了。我感觉there be这块错了, 即使曾经有这样的细菌死了,不代表没有活的?如果把there be改成all这样的话,我会觉得E跟D比较难比较。
作者: fengchen318    时间: 2011-5-25 23:11
文章的关键点:
  因为:  1、不同星球上的细菌具有显著的不同点;
             2、地球上的细菌没有发现这样的不同点。

  因此:即使地球上曾经有火星上的细菌,也已经死了。

  这个里面有个潜在的假设,就是这批细菌是地球上的细菌。这点是有错误,比如地球上现在的细菌都是从火星来的,地球原本没有细菌呢?

 E选项:
 是否有细菌来自于地球然后死了。我感觉there be这块错了, 即使曾经有这样的细菌死了,不代表没有活的?如果把there be改成all这样的话,我会觉得E跟D比较难比较。
-- by 会员 mudiduange (2011/5/25 17:01:40)

还是没太明白E。。。不好意思。。。
作者: mudiduange    时间: 2011-8-4 21:05
E选项说的是:作者没有考虑到是否有些产生于地球上的细菌后来死了。

这一点作者的确没有说,但这一点是不是一个flaw呢?
咱们想一下,细菌是生物,那么生老病死也都是正常现象。所以即使有的已经死了,有的还活着,都不影响得出结论啊。  

这里的关键点只要是说这些细菌就是产生于地球上的,就OK。




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