大牛看过来~~为什么A不对啊？

songhanxiao · 发表于 2010-9-24 16:44:08

The only physical factor preventing a human journey to Mars has been weight. Carrying enough fuel to propel a conventional spacecraft to Mars and back would make even the lightest craft too heavy to be launched from Earth. A device has recently been invented, however, that allows an otherwise conventional spacecraft to refill the craft’s fuel tanks with fuel manufactured from the Martian atmosphere for the return trip. Therefore, it is possible for people to go to Mars in a spacecraft that carries this device and then return.

Which one of the following is an assumption on which the argument depends?

A.   The amount of fuel needed for a spacecraft to return from Mars is the same as the amount of fuel needed to travel from Earth to Mars.
B.   The fuel manufactured from the Martian atmosphere would not differ in composition from the fuel used to travel to Mars.
C.   The device for manufacturing fuel from the Martian atmosphere would not take up any of the spaceship crew’s living space.
D.   A conventional spacecraft equipped with the device would not be appreciably more expensive to construct than current spacecraft typically are.
E.   The device for manufacturing fuel for the return to Earth weighs less than the tanks of fuel that a conventional spacecraft would otherwise need to carry from Earth for the return trip.

橘子骨头 · 发表于 2010-9-24 16:48:18

选C么?

songhanxiao · 发表于 2010-9-24 16:49:32

答案是E

橘子骨头 · 发表于 2010-9-24 16:51:23

啊··我觉得这道题是要补充说明一下这个device，就在CE徘徊了一下··但是E有点看不明白，其实C也挺不对的。真纠结

songhanxiao · 发表于 2010-9-24 16:55:10

C的话是跟crew的生活没有关系的吧。
A怎么错了啊？

橘子骨头 · 发表于 2010-9-24 17:04:05

对的，对的··我没看清···

首先，你看啊。飞船上不去火星，最主要的问题重量问题，装不了那么多燃料
接着后面提出一个新的device，这个新的device让飞船能上火星成为可能，所以我看完题目就会推测，这个假设应该就是关于这个device的。那就剩C和E选项了，我刚题目没有看清。题干中都没有对device重量的描述，这是个缺口，而E选项刚好补上了这个缺口。C就是打酱油的了。

至于A选项好像没什么必要吧，我看前几个字就排除了。这句话我觉得都有点问题，为什么要一样多啊，可多可少都没问题啊，燃料成分可以不一样嘛，如果A是对的话，B都有可能的。

橘子骨头 · 发表于 2010-9-24 17:05:02

The only physical factor preventing a human journey to Mars has been weight.

我觉得这句话是个关键

songhanxiao · 发表于 2010-9-24 17:10:08

分析的很有道理！
不过我困惑A的原因是如果要用那个device去 refill的话，如果来回需要的 fuel不一样多，那么可能导致回来的时候飞不回来。我是觉得会不会至少有这个基础？

songhanxiao · 发表于 2010-9-24 17:11:20

对，所以B肯定是不可能，因为它讲的是成分。但是A也提到了Amount。。。

大牛看过来~~为什么A不对啊？

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大牛看过来~~为什么A不对啊 ？

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大牛看过来~~为什么A不对啊？