1.Since heat naturally moves from hotter regions to cooler ones, the heat from the earth's center flows outwards towards the surface. In this way, it transfers to the next layer of rock. If the temperature is high enough, some of this rock melts and forms magma(岩浆). The magma ascends in its turn towards the earth's surface. It often remains well below the earth's surface, creating vast areas of hot rock. In such regions, there are deep cracks, which allow rainwater to descend underground. Some of the heated rainwater travels back up to the earth's surface where it will appear as a hot spring. However, if this ascending hot water reaches a layer of impermeable(不可渗透的)rock, it remains trapped, forming a geothermal reservoir. If geothermal reservoirs are close enough to the surface, they can be reached by drilling wells. Hot water and steam shoot up the wells naturally, and can be used to produce electricity in geothermal power plants.
2.A few geothermal power plants depend on dry-stem reservoirs which produce steam but little or no water. In these cases, the steam is piped up directly to provide the power to spin a turbine generator. The first geothermal power plant, constructed at Lardarello in Italy, was of this type, and is still producing electricity today.
3.Most currently operating geothermal power plants are either "flash" steam plants or binary(双重的)plants. Flash plants produce mainly hot water ranging in temperature from 300° to 700°Fahrenheit. This water is passed through one or two separators where released from the pressure of the underground reservoir, it "flashes" or boils into steam Again, the force of this steam provides the energy to spin the turbine and produce electricity. The geothermal water and steam are then reinjected directly back down into the earth to maintain the volume and pressure of the reservoir. Gradually they will be reheated and can then be used again.
4.A reservoir with temperatures below 300° Fahrenheit is not hot enough to flash steam but it can still be used to generate electricity in binary fluid. The steam from this is used to power the turbines. As in the flash steam plant, the geothermal water is recycled back into the reservoir.
23.【题干】Paragraph1_____
【选项】
A.Dry steam plants
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam
【答案】C
【解析】
24【题干】Paragraph2_____
【选项】
A.Dry steam plants
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam
【答案】A
【解析】
25【题干】Paragraph3_____
【选项】
A.Dry steam plants
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam
【答案】E
【解析】
26【题干】Paragraph4_____
【选项】
A.Dry steam plants
B.Binary plants
C.Origin of geothermal energy
D.Generation of electricity
E.Flash steam plants
F.Recyclable water and steam
【答案】F
【解析】
27.【题干】A geothermal reservoir is formed when hot water is trapped under _____.
【选项】
A.the energy to turn a turbine
B.impermeable rock
C.one or two separators
D.turbine operator
E.little or no water
F.hot springs
【答案】B
【解析】
28.【题干】A dry-steam reservoir produces steam with _____.
【选项】
A.the energy to turn a turbine
B.impermeable rock
C.one or two separators
D.turbine operator
E.little or no water
F.hot springs
【答案】E
【解析】
29.【题干】Flash plants produce hot water through _____.
【选项】
A.the energy to turn a turbine
B.impermeable rock
C.one or two separators
D.turbine operator
E.little or no water
F.hot springs
【答案】C
【解析】
30.【题干】In a binary plant, the heat of the geothermal water can be converted into _____.
【选项】
A.the energy to turn a turbine
B.impermeable rock
C.one or two separators
D.turbine operator
E.little or no water
F.hot springs
【答案】A
【解析】
阅读理解第一篇
Black Holes Trigger Stars to Self-Destruct
Scientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close. The black hotels gravity pulls harder on the nearest part of the star, an imbalance that pulls the star apart over a period of minutes or hours, once it gets close enough.
Scientists say this Uneven pulling is not the only hazard facing the star. The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough to destroy the star from within. Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon, France, carried out computer simulations of the final moments of such an unfortunate star's life，as it veered towards a supermassive black hole.
When the star gets close enough, the uneven forces flatten it into a pancake shape. Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart. But other studies had suggested that the picture would be complicated by shock waves generated during the flattening process and that no nuclear explosion should occur.
The new simulations investigated the effects of shock waves in detail，and found that even when their effects are included，the conditions favor a nuclear explosion. "There will be an explosion of the star-it will be completely destroyed," Brassart says. Although the explosion obliterates the star, it saves some of the star's matter from being devoured by the black hole. The explosion is powerful enough to hurl much of the star's matter out of the black hole's reach, he says.
The devouring of stars by black holes may already have been observed, although at a much later stage. It is thought that several months after the event that rips the star apart，its matter starts swirling into the hole itself. It heats up as it does so, releasing ultraviolet light and X-rays.
If stars disrupted near black holes really do explode, then they could in principle allow these events to be detected at a much earlier stage, says Jules Hatpern of Columbia University in New York, US. "It may make it possible to see the disruption of that star immediately if it gets hot enough," he says.
Brassart agrees. "Perhaps it can be observed in the X-rays and gamma rays, but it's something that needs to be more studied," he says. Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos, New Mexico, US, says the deaths of these stars are difficult to simulate, and he is not sure whether the researchers have proven their case that they explode in the process.
31.【题干】Something destructive could happen to a star that gets too close to a black hole. Which of the following destructive statements is NOT mentioned in the passage?
【选项】
A.The black hole could tear apart the star.
B.The black hole could trigger a nuclear explosion in the star.
C.The black hole could dwindle its size considerably.
D.The black hole could devour the star.
【答案】C
【解析】
32.【题干】According to the third paragraph，researchers differed from each other in the problem of_____
【选项】
A.whether nuclear reaction would occur.
B.whether the stars would increase its density and temperature.
C.whether shock waves would occur.
D.whether the uneven forces would flatten the stars.
【答案】A
【解析】
33.【题干】According to the fourth paragraph，which of the following is NOT true?
【选项】
A.No nuclear explosion would be triggered inside the star.
B.The star would be destroyed completely.
C.Much of the star's matter thrown by the explosion would be beyond the black hole's reach.
D.The black hole would completely devour the star.
【答案】D
【解析】
34.【题干】What will happen several months after the explosion of the star?
【选项】
A.The star's matter will move further away from by the black hole.
B.The black hole's matter will heat up.
C.The torn star's matter will swirl into the black hole.
D.The black hole's matter will release ultraviolet light and X-rays.
【答案】C
【解析】
35.【题干】According to the context，the word "disruption" in Paragraph 6 means_____
【选项】
A."Confusion."
B."Tearing apart."
C."Interruption."
D."Flattening."
【答案】B
【解析】
阅读理解第二篇
Deforestation and Desertification(沙漠化)
TheSahel zone lies between the Saharadesert and the fertile savannahs(热带大草原)ofnorthern Nigeria and South Sudan. The word sahel comes from Arabic and means marginal or transitional ,andthis is a good description of thesesemi-arid(半干旱)lands,whichoccupy much of the Western African countries of Mail,Mauritania,Niger,and Chad.
Unfortunately, over the last century theSahara desert has steadily crept southwards eating into once productive Sahellands. United Nations surveys show that over 70 percent of the dry land inagriculture use in Africa has deterioratedover the last 30 years. Droughts have become more severe, the most recentlasting over twenty years in parts of the Sahel region. The same process ofdesertification is taking place across southern Africa as the Kalahari desertadvances into Botswana and parts of South Africa.
One ofthe major causes of this desert advance ispoor agricultural land use, driven by the pressures of increasing population.Overgrazing一 keeping too many farm animals on the land一means that grasses and other plants cannot recover, and scarce water suppliesare exhausted. Overcultivation一 tryingto grow too many crops on poor land一 resultsin the soil becoming even less fertile and drier, and beginning to break up. Soilerosion (侵蚀) follows, and the land turns into desert.
Another cause of desertification is loss of tree cover. Trees are cutdown for use as fuel and to clear land for agricultural use. Tree roots help tobind the soil together, to conserve moisture, and to provide a habitat forother plants and animals. When trees are cut down, the soil begins to dry andloosen, wind and rain erosion increase, other plant species die, and eventuallythe fertile top soil may be almost entirely lost, leaving only bare rock anddust.
The effects of loss of topsoil and increased drought are irreversible. Theyare,however, preventable. Careful conservation of tree cover and sustainableagricultural land use have been shown to halt deterioration of soils and lessenthe effects of shortage of rainfall. One project in Kita in south-west Malifunded by UNDP has involved local communities in sustainable management offorest,while at the same time providing a viable(有活力的)agriculturaleconomy. This may be a model for similar projects in otherWest African countries.
35 order to prevent desertification,the author proposes ___.
A. making good use of international aids
B. developing a sustainableagricultural economy
C. gaining international support
D. converting agricultural land intoforest
答案：b
36.The Sahel zone is an area which ___.
A. is covered with sad and grass
B. has a long history
C. occupies much of South Nigeria
D. belongs to Sudan
答案：a
37. What is the situation about thedesertification in Africa?
A. The deserts are replaced withgrasslands
B. The deserts are expanding
C. the deserts are moving northwards
D. the deserts are being deserted
答案：b
38. The word “deteriorated ” in paragraph2 means ___.
A. deepened
B. suffered
C. slipped
D. worsened
答案：d
39. What is the root causeof desertification?
A. poor farming
B. overpopulation
C. radical climate change
D. disappearance of rare plant species
答案：a
40. In order to prevent desertification,the author proposes ___.
A. making good use of international aids
B. developing a sustainableagricultural economy
C. gaining international support
D. converting agricultural land intoforest
答案：b
阅读理解第三篇
OlderVolcanic Eruptions
Volcanoes were more destructive in ancient history, not because theywere bigger，but because the carbon dioxide(二氧化碳)theyreleased wiped out life with greater ease.
Paul Wignall from the University of Leeds was investigating the linkbetween volcanic eruptions and mass extinctions. Not all volcanic eruptionskilled off large numbers of animals, but all the mass extinctions over the past300 million years coincided with huge formations of volcanic rock. To hissurprise, the older the massive volcanic eruptions were, the more damage theyseemed to do. He calculated the "killing efficiency" for thesevolcanoes by comparing the proportion of life they killed off with the volumeof lava (熔岩) that they produced. He found that sizefor size, older eruptions were at least 10 times as effective at wiping outlife as their more recent rivals
The Permian (二叠纪)extinction, for example, which happened 250 million years ago, is marked byfloods of volcanic rock in Siberia that cover an area roughly the size ofwestern Europe. Those volcanoes are thought to have pumped out about 10gigatonnes (十亿吨) of carbon as carbon dioxide. The globalwarming that followed wiped out 80 percent of all marine genera (种类)at the time, and it took 5 million years for the planet to recover. Yet 60million years ago, there was another huge amount of volcanic activity andglobal warming but no mass extindtion. Some animals did disappear but thingsreturned to normal within tens of thousands of years. "The most recentones hardly have an effect at all," Wignall says. He ignored theextinction which wiped out the dinosaurs (恐龙) 65million years ago, because many scientists believe it was primarily caused bythe impact of an asteroid (小行星). Hethinks that older volcanoes had more killing power because more recent lifeforms were better adapted to dealing with increased levels of CO2.
Vincent Courtillot, director of the Paris Geophysical Institute in France,says that Wignall's idea is provocative. But he says it is incredibly hard todo these sorts of calculations. He points out that the killing power ofvolcanic eruptions depends on how long they lasted. And it is impossible totell whether the huge blasts lasted for thousands
or millions of years. He also adds that itis difficult to estimate how much lava prehistoric volcanoes produced, and thatlava volume may not necessarily correspond to carbon dioxide emissions.
41.Older volcanic eruptions did moredamage than more recent ones because
A. older volcanoes were brighter.
B. carbon dioxide made the earth muchwarmer
C. older volcanoes were hotter
D. carbon dioxide killed off life moreeasily
答案：d
42. Wignall calculated the killing powerof those older volcanic eruptions by
A. estimating how long they lasted
B. counting the dinosaurs they killed
C. comparing the proportion of lifekilled with the volume of lava produced
D. studying the chemical composition oflava
答案：c
43. When did dinosaurs become extinct?
A. 300 million years ago.
B. 250 million years ago
C. 65 million years ago
D. 60 million years ago
答案：c
44. It can be inferred from Paragraph 3that the cause of dinosaur extinction is_______
A. a political issue.
B. self-evident.
C. quite certain
D. controversial
答案：d
45. What is the main thesis of thearticle?
A. Volcanic eruptions are not alwaysdeadly.
B. Carbon dioxide emissions often giverise to global warming.
C. Older volcanic eruptions are moredestructive
D. It is not easy to calculate the killingpower of a volcanic eruption
答案：c
补全短文
Researchers Discover Why Humans Began Walking Upright
Most of us walk and carry items in our hands every day. These are seemingly simple activities that the majority of us don’t question. _____(46) The team of researchers from the U. S., England, Japan and Portugal investigated the behavior of modern-day chimpanzees as they competed for food resources，in an effort to understand what ecological settings would lead a large ape — one that resembles the 6 million-year old ancestor we shared in common with living chimpanzees — to walk on two legs.
"These chimpanzees provide a model of the ecological conditions under which our earliest ancestors might have begun walking on two legs", said Dr. Richmond.
The research findings suggest that chimpanzees switch to moving on two limbs instead of four in situations where they need to monopolize a resource._____(47)Over time, intense bursts of bipedal activity may have led to anatomical changes that in turn became the subject of natural selection where competition for food or other resources was strong.
Two studies were conducted by the team in Guinea. The first study was conducted by the team in Kyoto University's "outdoor laboratory" in a natural clearing in Bossou Forest. _____(48)The chimpanzees' behavior was monitored in three situations: when only oil palm nuts were available, when a small number of coula nuts were available，and when coula nuts were the majority available resource.
When the rare coula nuts were available only in small numbers, the chimpanzees transported more at one time. Similarly, when coula nuts were the majority resource, the chimpanzees ignored the oil palm nuts altogether. _____(49)
In such high-competition settings，the frequency of cases in which the chimpanzees started moving on two legs increased by a factor of four. Not only was it obvious that bipedal movement allowed them to carry more of this precious resource, but also that they were actively trying to move as much as they could in one go by using everything available-even their mouths.
The second study, by Kimberley Hockings of Oxford Brookes University, was a 14-month study of Bossou chimpanzees crop-raiding, a situation in which they have to compete for rare and unpredictable Resources. _____(50)
46.【题干】_____
【选项】
A.Standing on two legs allows them to carry much more at one time because it frees up their hands.
B.But an international team of researchers, including Dr. Richmond from GW's Columbian College of Arts and Sciences，have discovered that human walking upright, may have originated millions of years ago as an adaptation to carrying scarce, high- quality resources.
C.Here, 35 percent of the chimpanzees activity involved some sort of bipedal movement, and once again, this behavior appeared to be linked to a clear attempt to carry as much as possible at one time.
D.XXXXXX
E.Researchers allowed the wild chimpanzees access to different combinations of two different types of nut — the oil palm nut，which is naturally widely available, and the coula nut, which is not.
F.The chimpanzees regarded the coula nuts as a more highly-prized resource and competed for them more intensely.
【答案】B
【解析】
47.【题干】_____
【选项】
A.Standing on two legs allows them to carry much more at one time because it frees up their hands.
B.But an international team of researchers, including Dr. Richmond from GW's Columbian College of Arts and Sciences，have discovered that human walking upright, may have originated millions of years ago as an adaptation to carrying scarce, high- quality resources.
C.Here, 35 percent of the chimpanzees activity involved some sort of bipedal movement, and once again, this behavior appeared to be linked to a clear attempt to carry as much as possible at one time.
D.XXXXXX
E.Researchers allowed the wild chimpanzees access to different combinations of two different types of nut — the oil palm nut，which is naturally widely available, and the coula nut, which is not.
F.The chimpanzees regarded the coula nuts as a more highly-prized resource and competed for them more intensely.
【答案】A
【解析】
48.【题干】_____
【选项】
A.Standing on two legs allows them to carry much more at one time because it frees up their hands.
B.But an international team of researchers, including Dr. Richmond from GW's Columbian College of Arts and Sciences，have discovered that human walking upright, may have originated millions of years ago as an adaptation to carrying scarce, high- quality resources.
C.Here, 35 percent of the chimpanzees activity involved some sort of bipedal movement, and once again, this behavior appeared to be linked to a clear attempt to carry as much as possible at one time.
D.XXXXXX
E.Researchers allowed the wild chimpanzees access to different combinations of two different types of nut — the oil palm nut，which is naturally widely available, and the coula nut, which is not.
F.The chimpanzees regarded the coula nuts as a more highly-prized resource and competed for them more intensely.
【答案】E
【解析】
49.【题干】_____
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