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标题: GMAT-5-40请教求解思路 [打印本页]

作者: sv2000 时间: 2005-11-11 13:51
标题: GMAT-5-40请教求解思路

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?

It fails to establish whether bacteria actually developed on Mars.

It fails to establish how likely it is that Martian bacteria were transported to Earth.

It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.

It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.

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

作者: yangsh 时间: 2005-11-11 14:26

作者: sv2000 时间: 2005-11-12 10:58
能解释一下吗？谢谢

作者: carolhide 时间: 2005-12-11 17:12

不同星球上的细菌的蛋白质结构有显著差别+地球上细菌的蛋白质结构都相同=>从火星来的细菌已经死绝了。

地球上细菌的蛋白质结构相同说明细菌来自同个星球，可以是地球自己的，也可以是火星的。

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