托福阅读TPO25(试题+答案+译文)第1篇-ThesurfaceofMars.docx
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1、托福阅读TPO25(试题+答案+译文)第1篇:ThesurfaceofMars TPO是我们常用的托福模考工具,对我们的备考很有价值,下面我给大家带来托福阅读TPO25(试题+答案+译文)第1篇:The surface of Mars。 托福阅读原文 【1】The surface of Mars shows a wide range of geologic features, including huge volcanoes-the largest known in the solar system-and extensive impact cratering. Three very larg
2、e volcanoes are found on the Tharsis bulge, an enormous geologic area near Marss equator. Northwest of Tharsis is the largest volcano of all: Olympus Mons, with a height of 25 kilometers and measuring some 700 kilometers in diameter at its base. The three large volcanoes on the Tharsis bulge are a l
3、ittle smaller-a “mere” 18 kilometers high. 【2】None of these volcanoes was formed as a result of collisions between plates of the Martian crust-there is no plate motion on Mars. Instead, they are shield volcanoes volcanoes with broad, sloping slides formed by molten rock. All four show distinctive la
4、va channels and other flow features similar to those found on shield volcanoes on Earth. Images of the Martian surface reveal many hundreds of volcanoes. Most of the largest volcanoes are associated with the Tharsis bulge, but many smaller ones are found in the northern plains. 【3】The great height o
5、f Martian volcanoes is a direct consequence of the planets low surface gravity. As lava flows and spreads to form a shield volcano, the volcanos eventual height depends on the new mountains ability to support its own weight. The lower the gravity, the lesser the weight and the greater the height of
6、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. Marss surface gravity is only 40 percent that of Earth, so volcanoes ri
7、se 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 o
8、n their slopes), some of them may still be at least intermittently active. Millions of years, though, may pass between eruptions. 【4】Another prominent feature of Marss surface is cratering. The Mariner spacecraft found that the surface of Mars, as well as that of its two moons, is pitted with impact
9、 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
10、 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 f
11、rom place to place and erasing surface features much faster than meteoritic impacts alone can obliterate them. 【5】As on the Moon, the extent of large impact cratering (i.e. craters too big to have been filled in by erosion since they were formed) serves as an age indicator for the Martian surface. A
12、ge estimates ranging from four billion years for Marss southern highlands to a few hundred million years in the youngest volcanic areas were obtained in this way. 【6】The detailed appearance of Martian impact craters provides an important piece of information about conditions just below the planets s
13、urface. Martian craters are surrounded by ejecta (debris formed as a result of an impact) that looks quite different from its lunar counterparts. A comparison of the Copernicus crater on the Moon with the (fairly typical) crater Yuty on Mars demonstrates the differences. The ejecta surrounding the l
14、unar crater is just what one would expect from an explosion ejecting a large volume of dust, soil, and boulders. However, the ejecta on Mars gives the distinct impression of a liquid that has splashed or flowed out of crater. Geologists think that this fluidized ejecta crater indicates that a layer
15、of permafrost, or water ice, lies just a few meters under the surface. Explosive impacts heated and liquefied the ice, resulting in the fluid appearance of the ejecta. 托福阅读试题 1.The word “enormous”(paragraph 1)in the passage is closest in meaning to A.important B.extremely large C.highly unusual D.ac
16、tive 2.According to paragraph 1, Olympus Mons differs from volcanoes on the Tharsis bulge in that Olympus Mons A.has more complex geologic features B.shows less impact cratering C.is taller D.was formed at a later time 3.The word “distinctive”(paragraph 1)in the passage is closest in meaning to A.de
17、ep. B.complex. C.characteristic. D.ancient. 4.According to paragraphs 1 and 2, which of the following is NOT true of the shield volcanoes on the Tharsis bulge? A.They have broad, sloping sides. B.They are smaller than the largest volcano on Mars. C.They have channels that resemble the lava channels
18、of volcanoes on Earth. D.They are over 25 kilometers tall. 5.The word “roughly” in the passage is closest in meaning to A.typically. B.frequently. C.actually. D.approximately. 6.In paragraph 3, why does the author compare Maxwell Mons on Venus to the Hawaiian shield volcanoes on Earth? A.To help exp
19、lain the relationship between surface gravity and volcano height. B.To explain why Marss surface gravity is only 40 percent of Earths. C.To point out differences between the surface gravity of Earth and the surface gravity of Venus. D.To argue that there are more similarities than differences betwee
20、n volcanoes on different planets. 7.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaningin important ways or leave out essential information. A.Although direct evidence of recent eruptions is lacking, s
21、cientists believe that these volcanoes were active as recently as 100 million years ago. B.Scientists estimate that volcanoes active more recently than 100 years ago will still have extensive impact cratering on their slopes. C.If, as some evidence suggests, these volcanoes erupted as recently as 10
22、0 million years ago, they may continue to be intermittently active. D.Although these volcanoes were active as recently as 100 million years ago, there is no direct evidence of recent or ongoing eruptions. 8.The word “considerably”(paragraph 3)in the passage is closest in meaning to A.frequently. B.s
23、ignificantly. C.clearly. D.surprisingly. 9.According to paragraph 4, what is demonstrated by the fact that cratersfill in much faster on Mars than on the Moon? A.Erosion from meteoritic impacts takes place more quickly on Mars than on the Moon. B.There is more dust on Mars than on the Moon. C.The su
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