GWD6-Q40

GWD6-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?

1. It fails to establish whether bacteria actually developed on Mars.
2. It fails to establish how likely it is that Martian bacteria were transported to Earth.
3. It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.
4. It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.
5. It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.

Why D? Thanks.

想像一下，一堆孩子中搞滴血认亲，找了半天说这里任何两个孩子的学都可以溶，所以这些孩子里没有外地人留下的。殊不知，这些孩子都是外地人的娃

条件：1、火星上的B可能通过M来到地球
      2、来自不同行星的B必然结构不同
      3、地球上现在所有的B结构都相同
结论：来自火星上的B肯定都灭亡了

题目要求找出这个推论的漏洞，D：如果地球上的B都来自火星，那么以上结论肯定都是错的；D有两层意思，一是地球上的B全部死掉了（即是E所说的意思）；二是替代者是都是来自火星的。而选E则不好，因为可能现在的B也可能来自金星、木星等等其他行星，可以说来自火星的都死掉了，不能削弱结论。

i still do not know the meaning

Could someone explain again

条件：1、火星上的B可能通过M来到地球
           2、来自不同行星的B必然结构不同
           3、地球上现在所有的B结构都相同
结论：来自火星上的B肯定都灭亡了

我是这么理解的，通过条件可以推出两种可能性：一、地球上现存的所有B都不是来自火星的；二、地球上现存的所有B都是来自火星的。显然作者假设的是 一、地球上现存的所有B都不是来自火星的。只有这个假设存在，作者才能得到合理的推得自己的结论。

如果要削弱原文，则攻击作者的假设，说所有地球现存的B都是从火星来的。

请指正：）

ETS在这个题上的狡猾点在于，老美换了一种我们一直接受的问法：

The argument is most vulnerable to which of the following criticisms?
     --> argument对下面的哪个批评最弱，也就是哪个批评最能说明问题

（理解这个问题非常关键，该问法的结果完全不同于以前的 what is the most vulernerable criticisms to the argument，哪个是批评得最弱的）

这题还真得小心，本来总是想着节约时间，题目扫一眼就好，现在题目也要仔细看。做阅读时在读的选项同样如此，总是在一个词上玩一个小花样，但是句子就截然不同。