托福阅读修辞目的题是阅读考试中比较常见的一种题型，tpo则是托福阅读备考最权威的材料，所以托福小编综合二者，为大家集中整理了tpo阅读中考察的修辞目的题及其对应的解析，供大家参考使用。本文带来的是TPO25-1的修辞目的题，一起来看看吧。
TPO25-1The Surface of Mars
Paragraph 3: The great height of Martian volcanoes is a direct consequence of the planet’s low surface gravity. As lava flows and spreads to form a shield volcano, the volcano’s eventual height depends on the new mountain’s ability to support its own weight. The lower the gravity, the lesser the weight and the greater the height of the mountain. It is no accident that Maxwell Mons on Venus and the Hawaiian shield volcanoes on Earth rise to about the same height (about 10 kilometers) above their respective bases-Earth and Venus have similar surface gravity. Mars’s surface gravity is only 40 percent that of Earth, so volcanoes rise roughly 2.5 times as high. Are the Martian shield volcanoes still active? Scientists have no direct evidence for recent or ongoing eruptions, but if these volcanoes were active as recently as 100 million years ago (an estimate of the time of last eruption based on the extent of impact cratering on their slopes), some of them may still be at least intermittently active. Millions of years, though, may pass between eruptions.
6. In paragraph 3, why does the author compare Maxwell Mons on Venus to the Hawaiian shield volcanoes on Earth?
○ To help explain the relationship between surface gravity and volcano height
○ To explain why Mars’s surface gravity is only 40 percent of Earth’s
○ To point out differences between the surface gravity of Earth and the surface gravity of Venus
○ To argue that there are more similarities than differences between volcanoes on different planets
解析：以Maxwell为关键词定位至第三段第四句，这句只是在比较，于是往前看，说gravity越低，高度越高，所以作者进行这个比较无外乎想证明这个结论，所以正确答案 A。C稍有迷惑性，但C的问题在于没有提及高度，只是单纯说不同 planet之间gravity的关系，错。 [3]火星上火山的可观的高度是该行星(相对)较低的地表重力导致的直接结果。当熔岩流淌和蔓延以形成盾状火山时，这座火山的最终高度取决于这座新生的山承载自身重量的能力。重力越低，重量就越小，山的高度就越高。如金星上的麦克斯韦山与地球上的夏威夷盾状火山从它们各自的基部算起海拔高度相同(大约10千米高)就不是什么巧合——地球与金星的地表重力相当。火星表面重力只有地球的40%，因此火星上的火山高度大致是地球的2.5倍。火星上的盾状火山是否还处于活跃期?科学家们没有直接证据显示这些火山近期是否喷发过，或是否正处于喷发阶段，但是如果这些火山近期的活跃状态一如一千万年前那般(这一最近的爆发期是根据火山斜坡上陨石坑的范围估算出来的)，它们当中的几个也许至少仍然会保持间歇性的活跃。然而，两次爆发之间也许间隔数百万年之久。
Paragraph 4: Another prominent feature of Mars’s surface is cratering. The Mariner spacecraft found that the surface of Mars, as well as that of its two moons, is pitted with impact craters formed by meteoroids falling in from space. As on our Moon, the smaller craters are often filled with surface matter-mostly dust-confirming that Mars is a dry desert world. However, Martian craters get filled in considerably faster than their lunar counterparts. On the Moon, ancient craters less than 100 meters across (corresponding to depths of about 20 meters) have been obliterated, primarily by meteoritic erosion. On Mars, there are relatively few craters less than 5 kilometers in diameter. The Martian atmosphere is an efficient erosive agent, with Martian winds transporting dust from place to place and erasing surface features much faster than meteoritic impacts alone can obliterate them.
10. In paragraph 4, why does the author point out that Mars has few ancient craters that are less than 5 kilometers in diameter?
○ To explain why scientists believe that the surface matter filling Martian craters is mostly dust
○ To explain why scientists believe that the impact craters on Mars were created by meteoroids
○ To support the claim that the Martian atmosphere is an efficient erosive agent
○ To argue that Mars experienced fewer ancient impacts than the Moon did
解析：定位至倒数第二句后，发现整个句子是个例子，然后看前句，发现同样是个例子，然后看后一句，就是第9题的那句话就可以找到答案 C 。
[4]火星表面的另一个突出特征是陨石坑。水手计划中的宇宙飞船发现在火星表面布满来自太空的流星撞击表面形成的陨石坑，火星的两颗卫星也是如此。与我们的月球类似，那些较小的陨石坑经常被一些物质填满(主要是灰尘)，这表明火星是一个干燥的沙漠世界。然而，与月球相比，火星上的陨石坑被填满的速度明显要快很多。在月球上，那些直径不足100米(对应深度大约在20米)的古老陨石坑主要因流星冲击而形成的尘埃的缘故而被填平了。而在火星上，只有相当少的一部分陨石坑直径小于5千米。火星大气是一种强效的腐蚀剂，加之火星上的风把灰尘从一个地方卷到另一个地方，较之仅仅是因流星冲击而形成的尘埃的作用，(火星上的)地表特征被消除得更快。
以上就是托福阅读TPO25-1中的修辞目的题及其解析，大家可以在备考的时候参考复习，希望能够帮助大家的考前准备。最后前程百利祝大家都能取得理想的托福考试成绩。
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