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.
我看答案是选b, 但是看大家讨论帖，是选d...confused.....作者: sdcar2010 时间: 2010-12-24 21:55
D is the answer. Because it is possible that Martian bacteria eventually outlived the Earth bacteria during evolution battles.作者: stevenvboy 时间: 2010-12-24 22:58
好像prep上有这题，记得答案似乎是D。作者: gwang5 时间: 2010-12-28 21:59
D无疑