求救！新prep2-97

jessiecg

97.    (28634-!-item-!-188;#058&003060)    (GWD 6-Q40)
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.


正确答案是D,但我不懂为什么。。。
我当时蒙了个B,求牛人帮忙顺一下思路。。

jessiecg

自己顶一下~
希望很快有人回答。。。

richardyam15

首先，题目说如果病毒来自于两个星球的话，就会有significant difference，但系由于地球现存的病毒都没有足够的difference让人信服是来自不同星球的。d讲的是如果地球上所有的病毒都来源于mars，他们就不需要different，结论也就被weaken了。

jessiecg

恩

明白了  

谢谢牛人！

tyn0328

求题目翻译...
还是不太懂.......

克瑞斯

richardyam15 发表于 2010-9-15 15:08
首先，题目说如果病毒来自于两个星球的话，就会有significant difference，但系由于地球现存的病毒都没有足 ...

解释的真好

moonshacheryl

richardyam15 发表于 2010-9-15 15:08
首先，题目说如果病毒来自于两个星球的话，就会有significant difference，但系由于地球现存的病毒都没有足 ...

同意！