From Prep

Jasmine10

Excuse me that I type in English, because I'm using school computer now.
I need help~~ NN brothers and sisters, please help me on the CR as following. Thanks so much~

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 of the following criticisms?

A. It fails to establish whether bacteria actually developed on Mars.
B. It fails to 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.

I chose D, however, the correct one is E...
E.

AnnieFFish

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

因此E选项不行。

AnnieFFish

这题是选D昂

在这个帖子看到一个忒有意思的了类比
“ 讲故事最容易理解

张三有n个儿子，如果都是一个爹生的，这n个儿子肯定都长的很像，因为这n个都长得很像，所以都是张三的儿子。

问weaken

答案： 其实这n个儿子 都是隔壁李四帮他生的”

http://forum.chasedream.com/thread-769886-1-1.html

xiaowanzi2015

原文：来自不同planets的细菌，含有不同的蛋白质结构，而这种蛋白质结构能够长存。（即隐含的就是这种细菌也能跟着长存）
推理：地球上的细菌不是来自于不同的星球，所以肯定死了。
意思就是：因为地球上的细菌不是来自于不同的星球（来自于不同星球的话，才能长存），所以地球上的细菌不能长存，所以也就是死了。

所以原文的推理是：地球上的细菌没有来自于不同的星球（因为这里只考虑是从火星上来的）——所以就不能活下来就死了。

削弱：D，你只看到了从火星上过来的细菌，你没有考虑从其他星球上过来的。也就是说你没有考虑到“是不是所有的细菌都 来自于火星”   

如果地球上除了火星来的细菌，还有从其他土星
水星等其他星球来的细菌的话，那么因为不同星球的细菌会导致长存的蛋白质，自然地球上的细菌不可能全死了。

sui28

这题不是D吗

hanshipeng

D是说：地球上细菌全都是来自火星的。
E是说：地球上有，火星带来的也有，但是地球上的后来死光光了。
两者都是说地球上最后都是单一结构的细菌。但是题目重点在于，题干忽略了地球细菌死光的可能性，而单方面认为只有火星死光了。
不知明白否？关键是重点，看题干最后一句话。

fdunan

本题我也做错了。
重新整理了一下原题论证思路：
前提：来自不同行星的菌种其蛋白质机构可能很不同，且不存在两种地球上的菌种区别足够大以至于它们来自不同星球
结论：菌种肯定不是来自火星，而是地球自己的。
但是，作者没有考虑到一种可能：这种细菌可能恰好全都来自火星（同样满足前提条件）。

fansail

前人NN：
火星的bacteria曾经达到过地球而且现在还存活着。有两条路可以走：1）当前的bacteria都是从火星上来的 2）当前存在的bacteria部分是地球原生，部分是从火星上来的。要支持1）则需要质疑题干中的假设即不同星球上的 bacteria 其 protein structure 是肯定不一样的，也就是要证明火星和地球上的 bacteria 的 protein structure是可以一样的。

ruizm

这道题结论是地球上的细菌不可能来自于火星。
e。是否起源于地球的细菌后来died out。是，则地球上的细菌只可能来自火星，削弱；否，则地球上的细菌只可能来自地球，不可能来自于火星，加强
d。现在地球上的所有细菌是否都来自于火星。是，则削弱；否呢？？所以answer should be E

Jasmine10

I even couldn't understand the general meaning of this passage talked about. This passage is the most crap passage I've ever met.