GWD-6-40

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.

为什么D正确,我理解不来,请大家帮忙了....谢谢!

D是正确的！

如果地球上所有的细菌全部来自火星，当然不可能有两种不同的结构，IF这个成立，那么文章的结论说来自火星的灭绝了就错了！因为现有的细菌来自火星，但却没有灭！

試著簡單解釋成這樣:

有理論認為細菌是發源於火星並藉由隕石被帶到地球上. 但是, 不同星球上的細菌其蛋白質應該要有結構上的不同, 且這種不同是不會隨時間發展而消失的 (persist over time...), 而目前地球上的細菌種類都不具有足夠的不同點證明他們來自不同星球. 因此, 即便地球上確實有細菌來自火星, 這些細菌也已經不存在了...

答案D, 見2樓的解釋, 很清楚... 我本來也選錯了的...

真绕，总算搞明白了。原文的结论太大胆了，答案呢就来个更大胆的。

请问选项E错在哪里了啊

E的这种情况也是一种可能啊

请大牛指教

虽然选了D,但对E也很困惑,感觉E和D表达的意思是一样的:"地球上的细菌都来自火星,即使有发源于地球的细菌,也死光了"?

难道是因为E可能有漏洞,既: 地球上除了可能有发源于地球和火星的细菌,还有可能有发源于其他星球的细菌?

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

前提：地球上的B都一样，不可能来自火星；结论：即使有B来到地球，也都死光光了（不能影响地球的B）—>削：地球上的B可能是从火星B发展而来（把GAP拎出来）

而E说的是“没有考虑到可能有起源于地球的B而后来灭绝了”，也就是说E认为以前在地球上曾经存在过B，后来死了。这个与火星的B到地球，进而影响地球的B是无关的

答案可真是夸张呢