单选题Since 1960, the fast-growing town of Hotstone, Arizona, has drawn water from the Gray River, which feeds Lake Mudfish. If the town’s water use continues to grow at its present rate, in about 20 years the water level of Lake Mudfish will inevitably decrease to the point that it can no longer support its biologically fragile population of fish.　 The prediction above is based on which of the following assumptions?A As the town’s water requirements grow, it will not be able to meet those requirements by drawing on water sources other than the Gray River.B Since 1960, the lake’s population of fish has become more biologically fragile.C The amount of water that the lake loses to evaporation each year will increase over the next two decades.D There are multiple sources of water besides the Gray River that feed into Lake Mudfish.E The town of Hotstone will be able to reverse its trend of increasing water use if it implements an aggressive water conservation program.

考题 EThe need to feed a growing population is putting much pressure on the world’s supply of water. With 97% of the world’s water too salty to be drunk or used in agriculture, the worldwide supply of water needs careful management, especially in agriculture. Although the idea of a water shortage（短缺）seems strange to someone fortunate enough to live in a high rainfull country, many of the world’s agricultural industries experience constant water shortages.Although dams can be built to store water for agricultural use in dry areas and dry seaons, the costs of water redistribution(重新分配)are very high. Notonly is there the cost of the engineering itself, but there is also an environmental cost to be considered. Where valleys(山谷)are flooded to create dams, houses are lost and wildlife homes destroyed. Besides, water many flow easily through pipes to fields,but it cannot be transported from one side of the world to the other. Each country must therefore rely on the management of its own water to supply its farming requirements.This is particularly troubling ro countries with agricultural industries in areas dependent on irrigation（灌溉）. In Texas, farmers’ overuse of irrigation water be resulted in a 25% redcution of the water stores. In the Central Valley area of south eastern USA, a huge water engineering project provided water for farming in dry vallege, but much of the water use has been poorly managed.Saudi Arabia’s attempts to grow wheat in desert areas have been the pumping of huge quantities of irrigation water from underground reserves. Because there is no rainfall in these areas, such reserves can only decrease, and it is believed that fifty years of pumping will see them run dry.72. From the first two paragraphs we learnt that _______.A.much of the world’s water is available for useB.people in high rainfll countries feel luckyC.the costs of water redistribution should be consideredD.water can be easily carried through pipes across the world

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考题 Which of the following is true?A.The water in Texas have been reduced by 75%.B.Most industries in the world suffer from water shortagers.C.The underground water in Saudi Arabia might run out in 50 years.D.Good management of water use resulted from the project in the Central Valley.

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考题 Passage FiveFrom the beginning rivers have played an important part in the life of man. Man of the earliest times used the rivers as a means of traveling. Today rivers still serve as a great waterway for the transport and people.In ancient times, man settled near rivers or on river banks and built up large empires.Water is the Nature's most precious gift to man. Man needs water to irrigate his crops, to cook and to wash. In nations all over the world rivers mean life and wealth. They feed and clothe the nations around them.Water is also a source of energy and power. Man constructs huge dams across the river to control the water for irrigation and get the energy needed to drive generators. The electrical power is then directed to homes, cities, factories and television stations.Man uses water each day. His main source of water comes from reservoirs, which in turn get their water from the rivers.Rivers also bring down soil and minerals from the mountains and deposit them on the plains building up rich river deltas for raising plants and crops. Fresh water life in rivers or in lakes fed by them provide man with food.In a small way rivers help to keep man in good health and provide for his amusements. Various forms of water sports keep man strong and healthy.Rivers have run on this earth long before man. Man's future ability to live is uncertain, but rivers will flow on forever.52. Rivers have been important to man______.A. since the last centuryB. for a very long timeC. since a few hundred years agoD. since a few years ago

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考题 Passage ThreeA group of scientists rowing toward the center of a lake saw something shocking. They turned back as fast as they could. What had they seen.? The lake was boiling!The group was investigating a crater lake in the mountains of St. Vincent. A crater lake is the mouth of a volcano that has been dormant for some time and has filled with water.This particular crater was the tip of a volcano called Soufriere, which erupted last in 1902. Since that time, it had not shown any signs of action. But in the fall of 1971, mountain climbers who had hiked near the lake returned to the lowlands with strange stories. They said the water had turned yellow and was giving off a smell like burnt eggs. A seething fog was rising from the lake's surface.Local scientists rushed to Soufriere to see if this might be the beginning of a new volcanic explosion. They found a huge black mass in the middle of the water. It was a great blob 1,000 feet long and 300 feet wide. Lava had pushed up through the bottom of the lake and formed a new island.The investigators wanted to make sure that the volcano was safe, and that the lava would not over- flow into the surrounding countryside. But they could never reach the island to study it, because the lava was so hot that the water around it bubbled and boiled.44. This passage is about ______.A. mountain climbingB. a boiling lakeC. a new volcanic islandD. a mysterious blob

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考题 Passage FiveThe Northern Pike is a very bad fish. It is a big, hungry fish, and swallows little fish such as trout and perch. Many Northern Pikes live in Lake Davis. They are killing all the smaller fish in the lake. The Northern Pike are a serious threat to the lake because they eat all the smaller fish. Soon, all other species of fish in the lake will be killed off. This is not healthy for the environment.Experts are afraid that the Northern Pike will swim out of Lake Davis through many smaller rivers that feed into the lake. They could spread all over the country and damage many other water environments. If that happens, it would be too late to stop the Northern Pike.For ten years, officials have been trying to remove the Northern Pike from Lake Davis. They haw. tried using nets, explosives and poisons. However, the Northern Pike population is still doing well in Lake Davis. Many people do not like the idea of using poison to kill the fish. They worry that the poi- sons are bad for humans who use the water. No trace of the poisons has ever been found in local wells, however.Scientists are going to try the poison again. This time, they will drain the lake before they add the poison to the water. A public hearing will be held to talk about the problem.52. Why are some people against the use of poisons to kill Northern Pike?A. Fishermen will be poisoned too.B. The poisons are expensive.C. They think that wells will be polluted.D. The lake will become unsafe.

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考题共用题干 WaterFrom the beginning,water has furnished man with a source of food and a highway to travel upon.The first civilization arose(51)________water was a dominant element in the environment,a challenge(52)______man's ingenuity.The Egyptians invented the 365一day calendar in response to the Nile's annual flooding. The Babylonians,(53)________were among the most famous lawmakers in ancient times,invented laws(54)_________ water usage.Water inspired the Chinese to build a 1,000-(55)________canal,a complex system which,after nearly 2,500 years,remains still practically(56)_______ and still commands the astonishment of engineers.But (57)_________never found complete solutions to their water problems.The Yellow River is also known as "China's Sorrow" ;it is so unpredictable and dangerous(58)_________in a single flood it has caused a million(59)________.Floods slowed the great(60)_________of the Indus River Valley,and inadequate drainage ruined (61)________of its land. Today water dominates man (62)_______it always has done.Its presence continues to(63)________the location of his homes and cities;its violent variability can(64)________man or his herds or his crops;its routes links him(65)________his fellows;its immense value may add to already dangerous political conflicts.There are many examples of this in our own time._________(51)A:where B:the placeC:when D:in the place

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考题共用题干 WaterFrom the beginning,water has furnished man with a source of food and a highway to travel upon.The first civilization arose(51)________water was a dominant element in the environment,a challenge(52)______man's ingenuity.The Egyptians invented the 365一day calendar in response to the Nile's annual flooding. The Babylonians,(53)________were among the most famous lawmakers in ancient times,invented laws(54)_________ water usage.Water inspired the Chinese to build a 1,000-(55)________canal,a complex system which,after nearly 2,500 years,remains still practically(56)_______ and still commands the astonishment of engineers.But (57)_________never found complete solutions to their water problems.The Yellow River is also known as "China's Sorrow" ;it is so unpredictable and dangerous(58)_________in a single flood it has caused a million(59)________.Floods slowed the great(60)_________of the Indus River Valley,and inadequate drainage ruined (61)________of its land. Today water dominates man (62)_______it always has done.Its presence continues to(63)________the location of his homes and cities;its violent variability can(64)________man or his herds or his crops;its routes links him(65)________his fellows;its immense value may add to already dangerous political conflicts.There are many examples of this in our own time._________(58)A:that B:/C:because D: which

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考题共用题干 WaterFrom the beginning,water has furnished man with a source of food and a highway to travel upon.The first civilization arose(51)________water was a dominant element in the environment,a challenge(52)______man's ingenuity.The Egyptians invented the 365一day calendar in response to the Nile's annual flooding. The Babylonians,(53)________were among the most famous lawmakers in ancient times,invented laws(54)_________ water usage.Water inspired the Chinese to build a 1,000-(55)________canal,a complex system which,after nearly 2,500 years,remains still practically(56)_______ and still commands the astonishment of engineers.But (57)_________never found complete solutions to their water problems.The Yellow River is also known as "China's Sorrow" ;it is so unpredictable and dangerous(58)_________in a single flood it has caused a million(59)________.Floods slowed the great(60)_________of the Indus River Valley,and inadequate drainage ruined (61)________of its land. Today water dominates man (62)_______it always has done.Its presence continues to(63)________the location of his homes and cities;its violent variability can(64)________man or his herds or his crops;its routes links him(65)________his fellows;its immense value may add to already dangerous political conflicts.There are many examples of this in our own time._________(56)A:mnuse B:for useC:byuse D:on use

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考题共用题干 The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water, birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them, lakes may mean terrible disasters.In 1984,poisonous gases exploded out of Lake Monoun and came down into the nearby villages,killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes.They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottom than other crater lakes.In fact, scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster.Now scientists from the United States,France,and Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.They stood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air.Near the top of the pipe,the team put several holes that could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level,computers will set off loud sirens（警报）and bright lights to warn the people in the villages.In that way,they will have time to escape from the dangerous gases.Which of the following statements about Lake Nyos and Lake Monoun is true?A:They were formed in 1984.B:They are at the top of two active volcanoes.C:They are not like most other crater lakes.D:Water in them turns over regularly.

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考题共用题干 Water一the Issue of This CenturyThe world is running short of freshwater. Populations are growing bigger and thirstier （渴的）,with the result that freshwater is becoming increasingly scarce（缺乏）.Half the world's wetlands have disappeared during the last century,while estimates suggest that wa- ter use will rise by 50% in the next 30 years.The World Bank report estimates that as much as half of the world's population,concentrated in Africa,the Middle East and south Asia,will face“severe water shortages”by 2025.Local water conflicts and the loss of freshwater ecosystems appear large in some re- gions.A similar picture emerges from the globe's salt water regions. Three-quarters of the world's people may live within 100km of the sea in 2025,putting even more pressure on stretched coastal ecosystems. Two thirds of fisheries（渔业）are exploited at or beyond their sustainable limits, and half the world's coral reefs（珊瑚礁）may perish in 100 years. Almost 60% of coral reefs and 34% of fish species are at risk from human activities,the Bank says.The report concludes that there is ample evidence to justify immediate and coordinated action to safeguard supplies and use water more efficiently.Fresh water consumption is rising quickly,and the availability of water in some regions is likely to become one of the most pressing issues of the 21st century.A third of the world's popu1ation一around two billion people一live in countries that are experiencing moderate to high water shortages.That proportion could rise to half or more in the next 30 years unless institutions（制度）change to ensure better conservation and alloca- tion of water.China is one country where the portents（征兆）are gloomy. The most waterstressed country in East Asia,China is exploiting 44%of its usable water,a figure projected to rise to6O%by 2020.Primary withdrawal of water of more than 60%is widely considered by water experts to exceed the environmental carrying capacity of a river basin system. AlthoughChina's total use appears still to be reasonable,it has several basins that are severely stressed environmentally.Withdrawals exceed environmental limits in Afghanistan and Pakistan,and will exceed them in India by 2020.In the Middle East and North Africa,only Morocco has unexploited water resources.The rest have exceeded environmental limits and many are mining aquifers （蓄水层）一bodies of water-bearing rock一the report says.Most developed countries will face water shortages in 20 years.A: RightB: WrongC: Not mentioned

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考题共用题干第三篇The Exploding Lakes of CameroonWhat comes to mind when you think of a lake?You probably imagine a pretty scene with blue water,birds,and fish.For the people in the northwestern Cameroon,however,the image is very different.For them,lakes may mean terrible disasters.In 1984, poisonous gases exploded out of Lake Monoun and came down into the nearby villages, killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.Lake Nyos and Lake Monoun are crater（火山口）lakes. They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However,poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake. In most crater lakes,these gases are released often because the water"turns over" regularly.That is,the water from the bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the reason for this fact,but as a result,these lakes have more gases trapped at the bottomthan other crater lakes.In fact,scientists who have studied Lakes Nyos and Monoun have found 16,000 times more gases.When a strong wind,cool weather,a storm,or a landslide（滑坡）causes the water to turn over suddenly,the gases escape in a violent explosion.In the past,no one knew when the gases might explode,so there was no way for the villagers to escape disaster. Now scientists from the United States,France,andCameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.Theystood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the bottom and the other end in the air. Near the top of the pipe,the team put several holesthat could be opened or closed by a computer.Now,when the gas pressure gets too high,the holes are opened and some of the gas-filled water shoots up through the pipe into the air like a fountain.With less pressure,a disastrous explosion is much less likely.However,the scientists are not sure that one pipe will be enough to prevent explosions.They hope to put in others soon and they plan to install a similar pipe and a computer system at Lake Monoun as well.To protect people nearby until all of the pipes are in place,the scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level, computers will set off loud sirens（警报）and bright lights to warn the people in the villages. That way,they will have time to escape from the dangerous gases.Lake Nyos and Lake Monoun explode becauseA:the gases rise to the top and mix with air.B:people from the villages turn over the water.C:scientists have put in a computer system.D:they have more gases trapped at the bottom than other crater lakes.

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考题 Deep inside a mountain near Sweetwater in East Tennessee is a bady?of water known as the Lost?Sea.It is listed by the Guinness Book of World Records as the world′s largest underground lake.The Lost Sea is part of an extensive and historic cave system called Craighead Caverns. The caverns have been known and used since the days of the Cherokee Indian nation.The cave?expands into a series of huge rooms from a small opening on the side of the mountain.Approximately?one mile from the entrance,in a room called-The Council Room",many Indian artifacts have been?found.Some of the items discovered include pottery,arrowheads,weapons,and jewelry. For many years there were persistent rumors of a large underground lake somewhere in a cave,but it was not discovered until 1905.In that year,a thirteen-year-old boy named Ben Sands crawled through a small opening three hundred feet underground.:He found himself in a large cave half filled?with water. Today tourists visit the Lost Sea and ride far out onto it in glass-bottomed boats powered by electric motors.More than thirteen acres of water have been mapped out so far and still no end to the lake has been found.Even though teams of divers have tried to explore the Lost Sea,the full extent of it is still unknown. The Lost Sea is unique because it is__________.A.part of a historical cave system B.the biggest underground lake in the world C.listed in the Guinness Book of World Records D.the largest body of water in Tennessee

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考题共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.The word"fraction"in the second paragraph means________.A:a large areaB:a very small amountC:an important systemD:a major source of information

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考题共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.Most of the fresh water on Earth________.A:is in the form of ice at the poles and on mountainsB:is stored undergroundC:is found in rivers and lakesD:comes from the rain

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考题共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.Liquid water only exists________.A: in the center of the earthB:on the surface of our planetC:in the coastal areas of the earthD:in a very narrow range of temperatures

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考题共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.There is more of rainfall________.A:over the mountains than over the riversB:over the rivers than over the mountainsC:over the land than over the oceansD:over the oceans than over the land

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考题共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.The total quantity of water on Earth________.A:has greatly increased in recent yearsB:remains almost unchangedC:is decreasing constantlyD:is affected by global warming

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考题共用题干 Where Did the Earth's Water Come From?Earth is located within the"snow line"of the solar system,the region closest to the Sun where H2 0 is primarily in liquid or gaseous form,if at all.______(46)The snow line phenomena is reflected in the water content of planets like Mercury,Venus,and Mars. Water is absent on Mercury.On Venus,H2O only exists as a trace element in the atmosphere.Mars only has a thin veneer of ice in its polar regions.In general,water is rare within the snow line.Why does Earth have so much water relative to the other inner planets?71%of the surface is covered in the oceans,more than half of which is deeper than 3,000 meters,with an approximate total volume of 1.3 billion cu km.______(47)There are various theories as to where all the Earth's water came from,but several theories have fared better than the others.______(48)When the Earth was in the process of forming,with a radius just 40%smaller than at present,it would have had enough gravity to hold on to a tenuous atmosphere with water vapor. The first water vapor on the planet would have come from the planet's internals,where volatile(low weight)chemicals would have a tendency to float to the top,and heavy chemicals(iron and nickel)would sink.Though the first of Earth's water came about through volcanism,this alone probably didn't produce enough to form stable pools on the surface.______(49)Comparing the isotope ratios of water on Earth and water from comets and asteroids has revealed that the majority of the Earth's water comes from asteroids.Throughout its history,Earth's water has increased in volume due to biological processes. In the early seas of Earth,hydrogen sulfide would have been in great supply,which,when reacted with carbon dioxide from the atmosphere during photosynthesis in sulfide-reducing bacteria,would have produced hydrogen,sulfur,and water.______(50)________（49）A: More water was added to the planet during several hypothesized large impacts from asteroids from the outer asteroid belt.B:We know that the oceans existed as early as 100 million years after the formation of the Earth.C:Still,the oceans only make up 0.023%of the Earth's total mass.D:Astronomers say Earth s water may have come from space.E:The snow line is located in the outerasteroid belt,between the orbits of Mars and Jupiter. F: Many geologists believe that the majority of Earth's water generated through this process.

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考题 The largest lake in Britain is( ). A.the Lake Neagh B.Windermere Water C.Coniston Water D.the Lake District

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考题单选题Which of the following most closely parallels the situation described in the first sentence of the text?A Although a town reduces its public services in order to avoid a tax increase, the town’s tax rate exceeds that of other towns in the surrounding area.B Although a state.passes strict laws to limit the type of toxic material that can be disposed of in public landfills, illegal dumping continues to increase.C Although a town’s citizens reduce their individual use of water, the town’s water supplies continue to dwindle, because of a steady increase in the total populating of the town.D Although a country attempts to increase the sale of domestic goods by adding a tax to the price of imported goods, the sate of imported goods within the country continues to increase.

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考题单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What happens in the end to the water from Lake Ontario?A It is used by the residents of Toronto.B It is returned to a place deep in the lake.C It is cooled down before being used again.D It is added to the water inside air-conditioning systems.

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考题单选题If you swim in a river or lake, be sure to investigate________is below the water surface. Often there are rocks or branches hidden in the water.A whatB whoC thatD whoever

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考题问答题Water Crisis in Spain　　There’ve been floods, gales and heat waves across Europe-and some lay the blame for the unpredictable weather on climate change.　　Spain is undergoing its worst drought for sixty years with many areas in the south of the country not seeing a drop of rain for months. Some reservoirs are nearly empty while the volume of water in some rivers is down to a third of its normal level.　　Guadalajara, in the centre of the country, used to be a prosperous tourist area. Its old Moorish name, ironically, means water running through rocks. But when Emma Jane Kirby visited the small town of Buendia, she found an ecological disaster area in the marketing.　　There’s a strange smell around the lake at Buendia, the sort of smell that greets you when you first open the fridge after a week or two away from home—a putrid stench of salad leaves that’ve begun to turn to compost in their cellophane bag. I’m reluctant to mention this to my companion, Marco ObisP0 because this after are is the place where he has spent every one of his summer holidays and a just few hours ago we were pouting over the family photograph books while he reminisced wistfully about his idyllic childhood.　　The problem is I don’t recognize this place as being the same one he showed me in the pictures Those images boasted bronzed children racing joyfully down a bank of emerald green grass towards a vast expanse of water so blue that the cornflower sky above looked dazzled. But this landscape is bleached and barren, the banks crusted white, the ponds patchy and the colour of thin ink.　　Guadalajara in the centre of Spain has been hit hard by drought. The rains haven’t come since spring last year, leaving the soil parched and lifeless, as cracked and scarred as the face of a small pox victim. The sun has sucked the life from anything that once had the energy to be green and stealthily, its hot tongue has lapped away at the lake’s edge reducing the reservoirs to a fifth of the size they were twenty years ago. As quickly as the water’s evaporated, so have the tourists—the holidaymakers from all over Europe with whom Marco played as a child have been lured away to other areas of Spain where swimming or sailing a boat can be done without fear of scraping knees or hulls on the lake bed.　　If the landscape is crying out for new water management, then it’s weeping with painful dust-dry tears. North east of Buendia, only the ancient Spanish pine forests seem able to sustain life, some atavistic survival instinct wing them triumph over droughts which long ago killed off the weaker competition. But the trees are now so dehydrated and sapless they’ve become irresistible to fire-two weeks ago, thirteen thousand hectares were lost to a spark from a barbecue-an inferno that also claimed the lives of eleven men. As far as the eye can see now, the hills are almost bare.

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考题单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.Which of the following is true?A Enwave's system is said to work only in cities located near the Great Lakes.B The water deep in Lake Ontario always remains at the same temperature.C Experts warn that the use of CFCs in Enwave' s system will add to global warming.D Toronto is now searching for new natural sources of water to use in its water supply.

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考题单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What is one problem with traditional air-conditioning systems?A The chemicals they use sometimes pollute the water supply.B They often damage the buildings that they are trying to cool.C There are not enough CFCs in the world to cool all the buildings.D The method they use to cool water is thought to harm the ozone layer.

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考题单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What is the function of the chillers in a traditional air-conditioning system?A They pump the air continuously to the units in each room.B They lower the temperature of the water in the system.C They help the water cool down naturally on the roof .D They gradually clean the water as it flows through the building.

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考题单选题请阅读 Passage 1，完成第 21~25小题。Passage 1These days，many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool，but they can also damage the environment.Since they use a lot of electricity，for instance，they contribute indirectly to global warming.In addition，the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons，or CFCs，that are believed to damage the Earth's ozone layer.Recently，though，a system has been built in the city of Toronto，Canada，that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings，water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building，it gradually becomes warmer.Finally，it reaches the roof ，where it is left to cool down naturally in a water tower.After that it is returned to the chillers，where the cycle begins again.Toronto lies on the shore of Lake Ontario，one of North America's Great Lakes，and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth，the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However，the water from the lake is not pumped directly into the air-conditioning systems.Instead，it is used to cool the water that is already inside the air-conditioning systems.After that，the lake water is added to the city's ordinary water supply.Enwave，the company that developed this deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used，no damage can be caused to the ozone layer.Not every city is located next to a large lake，but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What is one advantage of Enwave 's new system?A It keeps buildings much cooler than other methods.B It can be used by large cities anywhere in the world.C It is much more energy-efficient than traditional systems.D It keeps water from being used for more than one purpose.

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