求助一道题

lebenkong

 
            
            
            
            
            
        

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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.

离子键

题目:

假设，火星上的bacteria被带到地球上．

事实：不同星球的bacteria蛋白质结构不同，且这种不同会世代相传，但是呢，地球上没有任意两种蛋白质的不同性都足以证明他们来自不同地方，即他们来自一个地方

所以，就算有火星来的，也全部死翘翘了

缺口：火星ＶＳ不同星球（有可能有其他星球）

削弱，找　否定＋加强项．

Ｄ项，不看ＦＡＩＬ　ＴＯ，即，地球上的bacteria全部来自火星，加强了题目，所以正确～

（按照缺口考虑正向想过来：如果全部都来自火星，那么＂no two bacterial strains on Earth are different enough to have arisen on different planets＂就是对的了）

太久不做了，我觉得我好象表达不太清楚，仅为抛砖引玉

[此贴子已经被作者于2008-1-16 22:04:22编辑过]

离子键

我好象看错题了,你等我完善一哈~

heatostrich

原文说，地球上没有bacteria差异大到可以算是来自两个星球的，所以就算有来自火星的，也死干净了。

原文忘记了，说不定现在地球上的bacteria都是来自火星上的~~