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 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?
A.It fails to establish whether bacteria actually developed on Mars.
B.It fails to establish how likely it is that Martian bacteria were transported to Earth.
C.It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.
D.It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.
E.It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out. 答案是D,我不懂╮(╯▽╰)╭。谢谢大侠了!!!
一些感想~ 我当时也做错了。后来发现没有关注文章的大前提:火星上的细菌被带到过地球。 按照这个理论,E选项是反前提的。 It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.该选项改变了大背景:火星上的细菌曾经被带到过地球。而直接认为地球上的细菌是原始的,是错的。
而正确选项: It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria。这个选项说地球上的细菌都是火星带来的。因此没有违反文章的大前提:火星带来过细菌。 并进一步说明有可能是地球上的细菌全是火星来的。
想了想为什么E不对
It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out
它只是说could have been,没有说是否所有地球上的细菌都die out
则
1. all bacteria that originated on Earth later died out --> 现存的都是来自Mars的细菌,因此才测不出不同的蛋白质 --> 所以不能得出来自MARS的细菌都die out了 . 可以削弱原文结论。
2. some bacteria that originated on Earth later died out --> 但是测不出不同的蛋白质 --> 可以推测来自MARS的细菌都die out了。
支持了原文结论