assumption, assumption

lily88888UID: 2828533

I have difficulty in "assumption" and "must be true" questions. Here is one assumption question. I am sure that I will learn from you smart people.

Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in oder of decreasing abundance.

The astronomers' argument relies on which one of the following assumptions?

A. There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.

B. Until space probes reach pluto, direct analysis of the atmosphere is impossible.

C. There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.

D. Nitrogen is fund in the atmosphere of the planet only if nitrogen ice is found on the surface of that planet.

E. A mixture of nitrogen, carbon monoxide, and methane is characteristic of the  substances from which the solar system formed.

I thought the answer would mention nitrogen, methane, and carbon monoxide. Did not know which one to pick when I did not see any choice had all of them. The answer is


















C.

aliciachloekongUID: 2828727

hmm

duijinxiaoziUID: 2585955

天体光谱分析（astronomical spectral analysis）
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题干提到：the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane。
说明这个行星上 只有 3种元素。
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选项C，就是确保没有其他元素在这个星球上。
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LZ 下次 可以把题号写出来，方便大家查阅。

lily88888UID: 2828533

what is "题号"? The question from which year, which test?Thanks dear two.

I am an old lady. Please allow me to take time getting used this website.

duijinxiaoziUID: 2585955

what is "题号"? The question from which year, which test?Thanks dear two.

I am an old lady. Please allow me to take time getting used this website.
lily88888 发表于 2010-6-8 23:39

嗯。:-)
就是哪年的考题。哪个section 的第几题。
热烈欢迎，大家来讨论。

umcwayneUID: 2674663

PT21-S2-Q19

兩個小問題

1. 我想確認最後一句話concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in oder of decreasing abundance.

意思是說, 冰越少表示氣體越多, 所以大氣含量由多至少的順序: nitrogen> carbon monoxide> methane?


2. 照板主所述結論強調的是除此三種氣體別無其他, 是小弟的語感不好嗎? 我以為他的重點是"順序", 要是結論加個only就清晰多了

謝謝

duijinxiaoziUID: 2585955

6# umcwayne
1）Since the proportion of any gas in such an atmosphere depends directly on how readily （容易地）the corresponding ice vaporizes
是气体越容易挥发，大气中所占比例越高。


2）结论：
astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in oder of decreasing abundance.
两个意思都说了：1）只含3种元素   2）含量的大小

duijinxiaoziUID: 2585955

Assumption Questions：
Conclusion （Valid）-----------》 Assumption （True）
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本题的Conclusion：
“astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in oder of decreasing abundance.”，大气中只有3种气体。
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premise：
the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes
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As the bible says，“An assumption is simply an unstated premise of the argument”。

Assumption：
我们就可以认为，只有3种frozen substance，即 nitrogen, methane, and carbon monoxide。
换句话说，除了这 3种frozen substance ，没有任何其他的 frozen substance。
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所以，assumption 最完美的描述应该是： “除了这 3种frozen substance ，没有任何其他的 frozen substance。” 【这个answer ，是最全面的，选项里没有】
C选项，是 subset statement ，也属于 correct answer。【这个answer ，说在methane 和carbon monoxide 之间，没有任何其他的 frozen substance。】

umcwayneUID: 2674663

謝謝, 版主在美國是嗎？