托福阅读备考之天文学习题

 　　在托福考试中，天文学科也从来都是被重点考察的学科之一。今天就来跟大家分享两道托福TPO模考软件中天文学的阅读题目。

　　第一道题目来自于TPO 8 Running Water on Mars

　　Paragraph 2: Outflow channels are probably relics¹ of catastrophic flooding on Mars long ago. They appear only in equatorial regions and generally do not form extensive interconnected networks. Instead, they are probably the paths taken by huge volumes of water draining from the southern highlands into the northern plains. The onrushing water arising from these flash floods likely also formed the odd teardrop-shaped “islands” (resembling the miniature versions seen in the wet sand of our beaches at low tide) that have been found on the plains close to the ends of the outflow channels. Judging from the width and depth of the channels, the flow rates must have been truly enormous-perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon river. Flooding shaped the outflow channels approximately 3 billion years ago, about the same times as the northern volcanic² plains formed.

　　Question: According to paragraph 2, all of the following are true of the outflow channels on Mars EXCEPT:

　　A. They formed at around the same time that volcanic activity was occurring on the northern plains.

　　B. They are found only on certain parts of the Martian surface.

　　C. They sometimes empty onto what appear to have once been the wet sands of tidal beaches.

　　D. They are thought to have carried water northward³ from the equatorial regions.

　　解析：题干问的是原文关于“outflow channels”的描述。在真正考试中，把原文阅读完毕再去和选项比较会花费较多时间。因此，比较合理的做题顺序是，先读选项，然后拿选项和原文信息去比对。

　　A选项说的是outflow channel的形成时间和火山活动在北部平原的发生时间是相同的。快速浏览原文，只有在最后一句提到了它们的形成时间，说大概在30亿年前，about引导的时间状语很重要，补充说明了这一时间和北部火山平原形成的时间相同。A正确。

　　B选项说的是火山形成的地点，只在火星表面的特定区域。看原文，第二句，说的是它们只在赤道区域出现。B也正确。

　　C选项说的是它们有时候会流到曾经的湿沙地上。原文在提到tidal beaches时，并没有提到这一信息，因此，C选项是不符合原文的。

　　D选项说的是河水从赤道（南）向北流动。和原文第三句话吻合：这些河流的走向是从南部高低到北部平原。

　　因此，本题的正确答案为C项。

　　第二道题目来自于 TPO 16 Planets in Our Solar System

　　Paragraph 4: Other dimensions along which the two groups differ markedly are density⁴ and composition. The densities⁵ of the terrestrial planets average about 5 times the density of water, whereas the Jovian planets have densities that average only 1.5 times the density of water. One of the outer planets, Saturn⁶, has a density of only 0.7 that of water, which means that Saturn would float in water. Variations in the composition of the planets are largely responsible for the density differences. The substances that make up both group of planets are divided into three groups-gases, rocks, and ices-based on their melting points. The terrestrial planets are mostly rocks: dense⁷ rocky and metallic⁸ material, with minor⁹ amounts of gases. The Jovian planets, on the other hand, contain a large percentage of the gases hydrogen and helium, with varying amounts of ices: mostly water, ammonia, and methane¹⁰ ices.

　　Question: Paragraph 4 mentions which of the following as a reason why terrestrial planets are dense?

　　A. They are made up of three groups of substances.

　　B. They are composed mainly of rocky and metallic materials.

　　C. They contain more ice than Jovian planets.

　　D. They contain relatively¹¹ small amounts of water.

　　解析：题干问的是类地行星密度较大的原因。那我们只需将做题重点锁定在原文描述“density”的信息上即可。原文中含有density的句子，第一句在说类地行星的密度和其他行星的密度比。第二句说的是土星密度。第三句说到行星结构的不同影响着密度的不同。后面进一步阐释组成行星的物质：气体，岩石以及冰。接着又提到类地行星主要由岩石组成。显然，这就是它密度大的原因。综合比较，应该选B。

1 relics   

[pl.］n.遗物，遗迹，遗产；遗体，尸骸

参考例句：

• The area is a treasure house of archaeological relics. 这个地区是古文物遗迹的宝库。
• Xi'an is an ancient city full of treasures and saintly relics. 西安是一个有很多宝藏和神圣的遗物的古老城市。

2 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

3 northward   

adv.向北；n.北方的地区

参考例句：

• He pointed his boat northward.他将船驶向北方。
• I would have a chance to head northward quickly.我就很快有机会去北方了。

4 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

5 densities   

密集( density的名词复数 )； 稠密； 密度（固体、液体或气体单位体积的质量）； 密度（磁盘存贮数据的可用空间）

参考例句：

• The range of densities of interest is about 3.5. 有用的密度范围为3．5左右。
• Densities presumably can be probed by radar. 利用雷达也许还能探测出气体的密度。

6 Saturn   

n.农神，土星

参考例句：

• Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

7 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

8 metallic   

adj.金属的；金属制的；含金属的；产金属的；像金属的

参考例句：

• A sharp metallic note coming from the outside frightened me.外面传来尖锐铿锵的声音吓了我一跳。
• He picked up a metallic ring last night.昨夜他捡了一个金属戒指。

9 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

10 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

11 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。