关于火星上的病毒问题~~~有句话没有读懂。

Helloface

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.
最后选D。
这句话是什么意思呢？“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.  ”

sunshengkun666

然而 ，来自不同星球的细胞系将可能具有重大的蛋白质结构方面的不同，这种不同将会持续下去。地球上没有两株细胞系足够不同而（表明）他们来自不同星球。这道题类似 于削弱题中找原因类型，正确答案应为题干中答案找错了，而是另外一个原因。所以这题的正确答案是不是因为细胞灭绝了，而是他们可能从原来的BACTERIA 中ARISE出来了，类似于进化的意思 。

paul1603

这道题不是选E吗？
原文说 地球上细菌可能来自火星和地球原生 这两种细菌的主要区别在于protein structure的不同
但是now科学家发现地球上的所有细菌没有这种显著的差别
造成这种现象的原因有两种
一是火星来的细菌后来都died out了 现在地球上的细菌都是地球原生的
二是地球原生的细菌后来died out了 现在地球上的细菌都是火星上来的
但是文章只考虑了第一点 没有考虑到第二点 而E选项所说正是应该考虑到第二点
个人理解 不知道对不对哦。。。

jackie19881102

这道题是D哦，不是E