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1、 为了帮助大家高效备考托福， 为大家带来托福 TPO42 阅读 Passage3 原文文本+题目+答案 解析，希望对大家备考有所帮助。 Callisto and Ganymede From 1996 to 1999,the Galileo spacecraft passed through the Jovian system,providing much information about Jupiters satellites.Callisto,the outermost of Jupiters four largest satellites,orbits the planet in sev
2、enteen days at a distance from Jupiter of two million kilometers.Like our own Moon.Callisto rotates in the same period as it revolves,so it always keeps the same face toward Jupiter.Its noontime surface temperature is only about-140C,so water ice is stable on its surface year- round.Callisto has a d
3、iameter of 4.820 kilometers,almost the same as that of Mercury.Its mass is only one-third as great,which means its density must be only one- third as great as well.This tells us that Callisto has far less of the rocky metallic materials found in the inner planets and must instead be an icy body thro
4、ugh much of its interior. Callisto has not fully differentiated,meaning separated into layers of different density materials.Astronomers can tell that it lacks a dense core from the details of its gravitational pull on the Galileo spacecraft during several very close flybys.This fact surprised scien
5、tists,who expected that all the big icy moons would be differentiated.It is much easier for an icy body to differentiate than for a rocky one,since the melting temperature of ice is so low.Only a little heating will soften the ice and get the process started,allowing the rock and metal to sink to th
6、e center and the slushy ice to float to the surface.Yet Callisto seems to have frozen solid before the process of differentiation was complete. Like our Moons highlands,the surface of Callisto is covered with impact craters.The survival of these craters tells us that an icy object can form and retai
7、n impact craters m its surface.In thinking of ice so far from the Sun,it is important not to judge its behavior from that of the much warmer ice we know on Earth;at the temperatures of the outer solar system,ice on the surface is nearly as hard as rock,and behaves similarly.Ice on Callisto does not
8、deform or flow like ice in glaciers on Earth.Callisto is unique among the planet-sized objects of the solar system in its absence of interior forces to drive geological evolution.The satellite was born dead and has remained geologically dead for more than four billion years. Ganymede,another of Jupi
9、ters satellites and the largest in our solar system,is also cratered,but less so than Callisto.About one-quarter of its surface seems to be as old and heavily cratered;the rest formed more recently,as we can tell by the sparse covering of impact craters as well as the relative freshness of the crate
10、rs.Ganymede is a differentiated world,like the terrestrial planets.Measurements of its gravity field tell us that the rock and metal sank to form a core about the size of our Moon,with a mantle and crust of ice floating above it.In addition,the Galileo spacecraft discovered that Ganymede has a magne
11、tic field,the signature of a partially molten interior.Ganymede is not a dead world,but rather a place of continuing geological activity powered by an internal heat source.Much of its surface may be as young as half a billion years. The younger terrain is the result of tectonic and volcanic forces S
12、ome features formed when the crust cracked,flooding many of the craters with water from the interior.Extensive mountain ranges were formed from compression of the crust,forming long ridges with parallel valleys spaced one to two kilometers apart.In some places older impact craters were split and pul
13、led apart.There are even indications of large- scale crustal movements that are similar to the plate tectonics of Earth. Why is Ganymede different from Callisto?Possibly the small difference in size and internal heating between the two led to this divergence in their evolution.But more likely the gr
14、avity of Jupiter is to blame for Ganymedes continuing geological activity.Ganymede is close enough to Jupiter that tidal forces from the giant planet may have episodically heated its interior and triggered major convulsions on its crust. paragraph 1 From 1996 to 1999,the Galileo spacecraft passed th
15、rough the Jovian system,providing much information about Jupiters satellites.Callisto,the outermost of Jupiters four largest satellites,orbits the planet in seventeen days at a distance from Jupiter of two million kilometers.Like our own Moon.Callisto rotates in the same period as it revolves,so it
16、always keeps the same face toward Jupiter.Its noontime surface temperature is only about-140C,so water ice is stable on its surface year- round.Callisto has a diameter of 4.820 kilometers,almost the same as that of Mercury.Its mass is only one-third as great,which means its density must be only one-
17、 third as great as well.This tells us that Callisto has far less of the rocky metallic materials found in the inner planets and must instead be an icy body through much of its interior. 1.According to paragraph 1,which of the following statements about Callisto is true? 【事实信息题】 A.It is the satellite
18、 closest to Jupiters surface B.Its surface temperature is constant at all times of the day. C.It has the same mass and diameter as the planet Mercury D.It completes one rotation every seventeen days. 答案：D 解 析 ： 根 据 原 文Callisto,the outermost of Jupiters four largest satellites,orbits the planet in se
19、venteen days at a distance from Jupiter of two million kilometers.可知，orbits the planet in seventeen days at a distance from Jupiter 对应 D 选项中的 one rotation every seventeen days.所以 D 选项正确。 2.According to paragraph 1,how do scientists know that Callisto is made up largely of ice? 【事实信息题】 A.A sample of
20、its interior was taken by the Galileo spacecraft in the late 1990s B.It has too low a density to contain much rocky metallic material C.With a noontime surface temperature of only about.140C.the ice on it never melts D.All of the bodies in the Jovian system are icy,because they are so far from the S
21、un. 答案：B 解析：根据 ice 定位至原文 This tells us that Callisto has far less of the rocky metallic materials found in the inner planets and must instead be an icy body through much of its interior.其中 far less of the rocky metallic materials 对应 B 选项中的 too low a density to contain much rocky metallic material.所以
22、 B 选项正确。 paragraph 2 Callisto has not fully differentiated,meaning separated into layers of different density materials.Astronomers can tell that it lacks a dense core from the details of its gravitational pull on the Galileo spacecraft during several very close flybys.This fact surprised scientists
23、,who expected that all the big icy moons would be differentiated.It is much easier for an icy body to differentiate than for a rocky one,since the melting temperature of ice is so low.Only a little heating will soften the ice and get the process started,allowing the rock and metal to sink to the cen
24、ter and the slushy ice to float to the surface.Yet Callisto seems to have frozen solid before the process of differentiation was complete. 3.Why does the author provide the information that“It is much easier for an icy body to differentiate than for a rocky one”?【事实信息题】 A.To support the claim that a
25、ll of the big icy moons are differentiated B.To suggest that Callisto may be a rocky body rather than an icy one C.To explain why scientists expected Callisto to be differentiated D.To refute the claim that Callisto could not differentiate because it was frozen solid 答案：C 解析：根据原文 This fact surprised
26、 scientists,who expected that all the big icy moons would be differentiated.可知 scientists expected 对应 C 选项中的 This fact surprised scientists.所以 C 选项正确。 4.All of the following questions are answered in paragraph 2 EXCEPT:【否定事实信 息题】 A.Why was Callisto frozen solid before differentiation was complete? B
27、.What allows the process of differentiation to get started? C.Why is it easier for an icy body to differentiate than a rocky one? D.How do astronomers know that Callisto lacks a dense core? 答案：A 解析：原文 Only a little heating will soften the ice and get the process started,allowing the rock and metal t
28、o sink to the center and the slushy ice to float to the surface.对应 B 选项。It is much easier for an icy body to differentiate than for a rocky one,since the melting temperature of ice is so low.对应 C 选项。 Astronomers can tell that it lacks a dense core from the details of its gravitational pull on the Ga
29、lileo spacecraft during several very close flybys.对应D选项。 所以选择A 选项。 paragraph 3 Like our Moons highlands,the surface of Callisto is covered with impact craters.The survival of these craters tells us that an icy object can form and retain impact craters m its surface.In thinking of ice so far from the
30、 Sun,it is important not to judge its behavior from that of the much warmer ice we know on Earth;at the temperatures of the outer solar system,ice on the surface is nearly as hard as rock,and behaves similarly.Ice on Callisto does not deform or flow like ice in glaciers on Earth.Callisto is unique a
31、mong the planet-sized objects of the solar system in its absence of interior forces to drive geological evolution.The satellite was born dead and has remained geologically dead for more than four billion years. 5.Which of the sentences below best expresses the essential information in the highlighte
32、d sentence in the passage?Incorrect choices change the meaning in important ways or leave out essential information.【句子简化题】 A.It should not be assumed that surface ice has the same characteristics wherever it is found B.Surface ice and rock are much more similar in temperature in the outer solar sys
33、tem than they are on Earth. C.The further away surface ice is from the Sun,the more its temperature differs from that of the warmer ice on Earth D.In the cold of the outer solar system,surface ice is so hard it behaves more like rock than like the warmer ice on Earth 答案：D 解析：highlighted 句子主干在后半部分，at
34、 the temperatures of the outer solar system,ice on the surface is nearly as hard as rock,and behaves similarly.注意之间的 比较关系，参考前半句话，much warmer ice we know on Earth.所以只有 D 选项符合句意。 6.According to paragraph 3,how is Callisto different from all other planet-sized objects in the solar system?【事实信息题】 A.It c
35、an form and retain impact craters on its icy surface B.It has ice glaciers that do not flow or deform. C.It has never had the interior forces required for geological evolution. D.It is more than four billion years old. 答案：C 解析：根据 planet-sized objects 定位至原文 its absence of interior forces to drive geo
36、logical evolution 可知，木卫星缺少内部动力来引发地质演化，其中 its absence 对应 C 选项的 It has never had,所以 C 选项正确。 本文是托福 tpo42 阅读答案解析：Callisto and Ganymede。 paragraph 4 Ganymede,another of Jupiters satellites and the largest in our solar system,is also cratered,but less so than Callisto.About one-quarter of its surface seem
37、s to be as old and heavily cratered;the rest formed more recently,as we can tell by the sparse covering of impact craters as well as the relative freshness of the craters.Ganymede is a differentiated world,like the terrestrial planets.Measurements of its gravity field tell us that the rock and metal
38、 sank to form a core about the size of our Moon,with a mantle and crust of ice floating above it.In addition,the Galileo spacecraft discovered that Ganymede has a magnetic field,the signature of a partially molten interior.Ganymede is not a dead world,but rather a place of continuing geological acti
39、vity powered by an internal heat source.Much of its surface may be as young as half a billion years. 7.The word“signature”in the passage is closest in meaning to【词汇题】 A.primary cause B.end result C.identifying mark D.by-product 答案：C 解析：signature,签名，信号，标志。 Primary cause,主因。 End result,最终结果。 Identifyi
40、ng mark,识别标记。 By- product, 副产品。所以 C 选项正确。 8.According to paragraph 4,each of the following provides evidence about Ganymedes interior EXCEPT【否定事实信息题】 A.Ganymedes large size B.measurements of Ganymedes gravity field C.the fact that Ganymede has a magnetic field D.the fact that Ganymede continues to b
41、e geologically active 答案：A 解析：原文 Measurements of its gravity field tell us that the rock and metal sank to form a core about the size of our Moon,对应 B 选项。the Galileo spacecraft discovered that Ganymede has a magnetic field,对应 C 选项。but rather a place of continuing geological activity powered by an in
42、ternal heat source,对应 D 选项。所以选 择 A 选项。 paragraph 5 The younger terrain is the result of tectonic and volcanic forces Some features formed when the crust cracked,flooding many of the craters with water from the interior.Extensive mountain ranges were formed from compression of the crust,forming long
43、ridges with parallel valleys spaced one to two kilometers apart.In some places older impact craters were split and pulled apart.There are even indications of large- scale crustal movements that are similar to the plate tectonics of Earth. 9.The word“Extensive”in the passage is closet in meaning to【词
44、汇题】 A.Unusual B.Large C.New D.Steep 答案：B 解析：extensive,大量的，广阔的。 Unusual,与众不同的。Large,大的。New,新的。Steep,陡峭的。所以 B 选项正确。 10.Paragraph 5 supports each of the following statements about Ganymede EXCEPT: 【否定事实信息题】 A.All water on it has always been frozen solid. B.There is evidence that part of its crust once
45、broke open C.Its crust has been subject to forces that have created mountains and valleys. D.Some of its older craters have been split apart by more recent geological activity 答案：A 解析：原文 Some features formed when the crust cracked 对应 B 选项，其中 crust cracked 对应 B 选项中的 crust once broke open.原文 Extensive
46、 mountain ranges were formed from compression of the crust,forming long ridges with parallel valleys spaced one to two kilometers apart.对应 C 选项。原文 In some places older impact craters were split and pulled apart.对应 D 选项。所以选择 A 选项。 paragraph 6 Why is Ganymede different from Callisto?Possibly the small
47、 difference in size and internal heating between the two led to this divergence in their evolution.But more likely the gravity of Jupiter is to blame for Ganymedes continuing geological activity.Ganymede is close enough to Jupiter that tidal forces from the giant planet may have episodically heated
48、its interior and triggered major convulsions on its crust. 11.According to paragraph 6,the differences in how Callisto and Ganymede evoked are most probably due to differences in their【事实信息题】 A.size and internal heating B.distance from Jupiter C.chemical and physical composition D.age 答案：B 解析：根据原文 G
49、anymede is close enough to Jupiter that tidal forces from the giant planet may have episodically heated its interior and triggered major convulsions on its crust.可知，Ganymede 距离木星更近，其中 Ganymede is close enough to Jupiter 对应 B 选项的 distance from Jupiter,所以选项 B 正确。 12.Look at the four squaresthat indicate where the following sentence could be added to the passage.【句子插入题】 The difference between Ganymede and Callisto,however,extend much further below the surface of the satellites. Where would the sentence best fit?Click on squareto add the sentence to the passage Ganymede,ano