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Pollution and Ecocrisis The problem of pollution is also of great social concern. Continued population increase, accompanied by a rise in the level of living standards, not only threatens to exhaust American resources but pollutes the environment to such an extent that production in the thickly settled area is impossible without damaging the health of the local residents. Smog, once an urban annoyance, is now recognized as a health risk, and the automobile has been pinpointed as the principal culprit. Heavy industries have been blamed for river, soil, air, noise and visual pollutions. DDT and other chemical remedies have been doing more ecological harm than the good that they may have brought along. Several decades ago, Americans dumped raw sewage into rivers and many industrial plants are now still dumping chemical pollutants into lakes, rivers and oceans. Oceans used to be and are still being considered to be a reserve of seafood. Today, after the oceans have become the home of all pollutants, this use of the oceans is being reduced at an alarming rate. The worst pollution threat is concentrated in and near large cities. There the people-made pollutants increasingly surpass the ability of air and water to dilute (冲淡；稀释) the contaminants (污染物) to safe levels. The natural ecological cycle depends on plants, which absorb some pollutants and release oxygen to the air. But near large cities, natural vegetation becomes scarce, and introduced trees, ornamental shrubs and gardens are far from adequate in absorbing motor vehicle and industrial air pollutants. Finally, some pollutants, most notably atomic waste, may continue to contaminate air, land, and water for thousands of years. Therefore, ecocrisis—ecocatastrophe or ecocide—has been for some time one of the major concerns of not only the ecoactivists and environmentalists, but of many scientists of other fields and the government authorities of many countries as well. Last but not least, there is the question of whether the people will eventually be able to solve all these problems. The American continent is a wealthy land inhabited by many able and well- educated people. There today, people have originated a life-style which is known to the world as being characteristic of a society of consumption—a life-style based on the prodigal (挥霍浪费的) use of material goods. They are using up many times their share of the earth’s resources at a rate unparalleled in history. And I am sorry to say that this life-style of American has been copied by the people of many developed countries, leading to the greatest problem of the modem world as a whole. So I must ask: Are the Americans apt enough to cooperate with other peoples to prevent over-population, resource exhaustion, the catastrophe of pollution and the wanton waste of wealth — problems which are basic to the solution of many outstanding economic, social and political problems? Only time will tell.
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更多 “问答题Pollution and Ecocrisis The problem of pollution is also of great social concern. Continued population increase, accompanied by a rise in the level of living standards, not only threatens to exhaust American resources but pollutes the environment to such an extent that production in the thickly settled area is impossible without damaging the health of the local residents. Smog, once an urban annoyance, is now recognized as a health risk, and the automobile has been pinpointed as the principal culprit. Heavy industries have been blamed for river, soil, air, noise and visual pollutions. DDT and other chemical remedies have been doing more ecological harm than the good that they may have brought along. Several decades ago, Americans dumped raw sewage into rivers and many industrial plants are now still dumping chemical pollutants into lakes, rivers and oceans. Oceans used to be and are still being considered to be a reserve of seafood. Today, after the oceans have become the home of all pollutants, this use of the oceans is being reduced at an alarming rate. The worst pollution threat is concentrated in and near large cities. There the people-made pollutants increasingly surpass the ability of air and water to dilute (冲淡；稀释) the contaminants (污染物) to safe levels. The natural ecological cycle depends on plants, which absorb some pollutants and release oxygen to the air. But near large cities, natural vegetation becomes scarce, and introduced trees, ornamental shrubs and gardens are far from adequate in absorbing motor vehicle and industrial air pollutants. Finally, some pollutants, most notably atomic waste, may continue to contaminate air, land, and water for thousands of years. Therefore, ecocrisis—ecocatastrophe or ecocide—has been for some time one of the major concerns of not only the ecoactivists and environmentalists, but of many scientists of other fields and the government authorities of many countries as well. Last but not least, there is the question of whether the people will eventually be able to solve all these problems. The American continent is a wealthy land inhabited by many able and well- educated people. There today, people have originated a life-style which is known to the world as being characteristic of a society of consumption—a life-style based on the prodigal (挥霍浪费的) use of material goods. They are using up many times their share of the earth’s resources at a rate unparalleled in history. And I am sorry to say that this life-style of American has been copied by the people of many developed countries, leading to the greatest problem of the modem world as a whole. So I must ask: Are the Americans apt enough to cooperate with other peoples to prevent over-population, resource exhaustion, the catastrophe of pollution and the wanton waste of wealth — problems which are basic to the solution of many outstanding economic, social and political problems? Only time will tell.” 相关考题
考题
Which may NOT be one of the causes for the rise of American Romantic Movement?
A.The westward territorial expansionB.The great increase in populationC.The victory of the settlers in the Indian warD.The rapid economic transformation
考题
Passage ThreeThe whole industrial process which makes many of the goods and machines we needand use in our daily lives, is bound to create a number of waste products whichupset the environmental balance or the ecological(生态的)balance as it is known. Many of these waste products can be prevented or disposed(处理) of sensibly, but clearly while more and more new goods are produced and made complex, there willbe new, dangerous wastes to be disposed of, for example, the waste products from nuclear powerstations. Many people therefore see pollution as only part of a larger and more complex problem, that is,the whole process of industrial production and consumption of goods. Others see the problem mainly inconnection with agriculture, where new methods are helping farmers grow more and more on theirland to feed our everincreasing population. However, the land itself is graduallybecoming worn out as it is being used, in some cases, too heavily, and artificialfertilizers(人造肥料) cannot bring back the balance.Whatever is underlying(潜在的)reasons, there is no doubt that much of the pollution caused could be controlled if only companies,individuals and governments would make more efforts. In the home there is an obvious need to control litter(杂乱的废物)and waste. Food is wrapped up three or four times in packages that all have to be disposed of; drinks areincreasingly sold in bottles or tins which cannot be reused. This not only causes a litter problem, but also isa great waste of resources, in terms of glass, metals and paper. Advertising has helped this process bypersuading many of us to buy things we don't want to buy. Pollution and waste continue to be a problemeveryone can help to solve by cutting out unnecessary buying, excess consumption and careless disposal ofthe products we use in our daily lives.44. The main cause of pollution is______.A. the production of new industrial goodsB. increased amounts of unnatural substanceC. our ever-increasing populationD. the release of artificial substances into the environment
考题
In the writer's view, the more new goods there are,______.A. the less pollution we haveB. the harder pollution can be done away withC. the more pollution there will beD. the more easily pollution can be controlled
考题
完形填空Many of the world’s pollution problems have been caused by the crowding of large groups of people into cities.Satisfying the 21 of the people leads to further polluting by industry.If the rapid increase in human population 22 at the present rate (比率), there may be much greater harm.Some scientists speak of the 23 in number of people as “Population Pollution”.About 2000 years ago, the world 24 was probably about 250 million.It reached a billion in 1850.By 1930 the population was two billion.It is 25 three and a half billion.It is expected to double by the year 2000.If the population continues to grow at the same 26 , there would be 25 billion people in the world a hundred years from now.Man has been using the earth’s 27 more and more rapidly over the years.Some of them are almost gone.Now many people believe that man’s greatest 28 is how to control the growth of this population.The materials in the world will not support the human population in time to come if the present rate of increase continues.29 there is over crowding in the cities and hunger in some countries.Can man’s rate of increase continue?Many people believe that human survival (幸存者) in the future 30 on the answer to the question.21.A.needsB.suppliesC.serviceD.supports22.A.stopsB.continuesC.slows downD.adds to23.A.increaseB.reduceC.countryD.improvement24.A.peopleB.situationC.populationD.land25.A.nowB.in the pastC.in the futureD.then26.A.placeB.timeC.rateD.result27.A coalB.oilC.minesD.resources28.A.problemB.powerC.planD.idea29.A.AlreadyB.YetC.StillD.Often30.A.feedsB.livesC.keepsD.depends
考题
People all over the world today are beginning to hear and learn more and more about the problem of pollution.Pollution is caused either by man s release of completely new and often artificial substances into the environment, or by releasing greatly increased amounts of a natural substance, such as oil tankers into the seaWhatever it' s underlying reasons, there is no doubt that much of the pollution caused could be controlled if only companies, individuals and governments would make more efforts In the home there is an obvious need to control litter and waste Food comes wrapped up three or four times in packages that all have to be disposed of: drinks are increa singly sold in bottles or tins which cannot be reused.This not only causes a litter problem, but also is a great waste of resources, in term of glass metals and paper.Advertising has helped this process by persuading many of us not only to buy things we neither want nor need, but also to throw away much of what we do buy Pollution and waste combine to be a problem everyone can help to solve by cutting out unnecessary buying, excess consumption and careless disposal of the products we use in our daily lives.21.The main cause of pollution isA the release of artificial or natural substances into the envIronmentB.the production of new industrial goodsC.increased amounts of a natural substance22.Much of the pol lut ion could be controlled if onlyA.people would pay more attention to the problemB.governments would take effective measuresC.all sides concerned would make more efforts23.Food packages, bottles and tins for drinks can causeA.air and water pollutionB.both a litter problem and a waster of resourcesC.to pay for the service24.Which of the following cannot help solving the problem of pollution?()A.Cutting out unnecessary buyingB.Eating.C.Reduce excess us25.What does the underlined word "litter" mean in Para.2?()A.not manyB.serious problemC.bits of waste things
考题
With pollution becoming an international problem, environment protection has been handled with greater care around the world. (翻译)
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共用题干
第三篇Preserve the EnvironmentThroughout history man has changed his physical environment in order to improve his way of life.With the tools of technology he has altered many physical features of the earth.He has transformed woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric power. Man has also modified the face of the earth by draining marshes and cutting through mountains tobuild roads and railways.However,man's changes to the physical environment have not always had beneficial results.Today, pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor- mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed. The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-vive on earth.Who would most probably disagree with conservationists?A:Industrialists.B:Ecologists.C:Businessmen.D:Environmentalists.
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共用题干
第三篇Preserve the EnvironmentThroughout history man has changed his physical environment in order to improve his way of life.With the tools of technology he has altered many physical features of the earth.He has transformed woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric power. Man has also modified the face of the earth by draining marshes and cutting through mountains tobuild roads and railways.However,man's changes to the physical environment have not always had beneficial results.Today, pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor- mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed. The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-vive on earth.According to the passage,pollution of the air and water is caused by__________.A:thousands of tons of gases coming out of the exhausts of motor vehiclesB:the changes of the environment that technology has brought to manC:the increasing amount of oil that has been producedD:industrial wastes discharged into rivers
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共用题干
第三篇Preserve the EnvironmentThroughout history man has changed his physical environment in order to improve his way of life.With the tools of technology he has altered many physical features of the earth.He has transformed woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric power. Man has also modified the face of the earth by draining marshes and cutting through mountains tobuild roads and railways.However,man's changes to the physical environment have not always had beneficial results.Today, pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor- mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed. The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-vive on earth.Man has changed his physical environment with a view to_________.A:altering the physical features of the earth B:modifying the face of the planetC:improving his surroundings'D:bettering his way of life
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共用题干
第三篇Preserve the EnvironmentThroughout history man has changed his physical environment in order to improve his way of life.With the tools of technology he has altered many physical features of the earth.He has transformed woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric power. Man has also modified the face of the earth by draining marshes and cutting through mountains tobuild roads and railways.However,man's changes to the physical environment have not always had beneficial results.Today, pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor- mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed. The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-vive on earth.The purpose of the writer is___________.A:to reduce modern technologyB:to improve man's way of lifeC:to warn people not to change the natural environmentD:to call attention to the protection of the natural environment
考题
根据下列内容，回答196-200题。
Water problems in the future will become more intense and more complex. Our increasingpopulation will tremendously increase urban wastes, primarily sewage. On the other hand, increas-ing demands for water will decrease substantially the amount of water available for diluting wastes.
Rapidly expanding industries which involve more and more complex chemical processes will pro-duce large volumes of liquid wastes, and many of these will contain chemicals which are poi-sonous. To feed our rapidly expanding population, agriculture will have to be intensified. This willinvolve ever-increasing quantities of agriculture chemicals. From this, it is apparent that drasticsteps must be taken immediately to develop corrective measures for the pollution problem.
There are two ways by which this pollution problem can be lessened. The first relates to thetreatment of wastes to decrease their pollution hazard. This involves the processing of solid wastesprior to disposal and the treatment of liquid wastes, or effluents, to permit the reuse of the wateror best reduce pollution upon final disposal.
A second approach is to develop an economic use for all or a part of the wastes. Farm manureis spread in fields as a nutrient or organic supplement. Effluents from sewage disposal plants areused in some areas both for irrigation and for the nutrients contained. Effluents from other process-ing plants may also be used as a supplemental source of water. Many industries, such as meat andpoultry processing plants,are currently converting former waste production into marketablebyproducts. Other industries have potential economic uses for their waste products.
The purpose of this passage is___________.A.to warn the reader of the dwindling water supply
B.to explain industrial uses of water
C.to acquaint the reader with water pollution problems
D.to demonstrate various measures to solve the pollution problem
考题
问答题Pollution 1)Pollution is a problem because man, in an increasingly populated and industrialized world，is upsetting the environment in which he lives. 2) Many scientists maintain that one of man's greatest errors has been to equate growth with advancement. 3) Now “growth” industries are being looked on with suspicion incase their side effects damage the environment and disrupt the relationship of different forms of life. 4) The growing population makes increasing demands on the world’s fixed supply of air, water and land. 5) This rise in population is accompanied by the desire of more and more people for a better standard of living. 6) The problem has been causing increasing concern to living things and their environment.
考题
问答题Pollution is a problem because man, in an increasingly populated and industrialized world, is upsetting the environment in which he lives. Many scientists maintain that one of man’s greatest errors has been to equate growth with advancement. Now “growth” industries are being looked on with suspicion in case their side effects damage the environment and disrupt the relationship of different forms of life, the growing population makes increasing demands on the world’s fixed supply of air, water and land.
考题
问答题Directions： Cars play an important role in modern society. But they are also responsible for a good part of air pollution in big cities. Write an essay on car and air pollution and base your composition on the outline below: （1）the serious problem of air pollution caused by cars; （2）your suggestions on how to deal with the problem. You should write about 150 words neatly on the ANSWER SHEET.
考题
问答题Directions： Cars play an important role in modern society. But they are also responsible for a good part of air pollution in big cities. Write an essay on car and air pollution and base your composition on the outline below: （1）the serious problem of air pollution caused by cars; （2）your suggestions on how to deal with the problem. You should write about 160-200 words neatly on the ANSWER SHEET.
考题
问答题Research published in May 1998 by the Department of the Environment, Transport and the Regions (DETR) showed that reducing coastal and river pollution and ensuring a reliable water supply were among the top environmental priorities for the public. All discharges to water in the UK require the consent of the appropriate regulatory authority. In England and Wales the Environment Agency’s principal method of controlling water pollution is through the regulation of all effluent discharges, including sewage, into groundwater, and inland and coastal waters. The Agency maintains public registers containing information about water quality, discharge consents, authorizations and monitoring. Applicants for consents to discharge have the right of appeal if they are dissatisfied with the Agency’s decision; most of these appeals are dealt with by the Planning Inspectorate, an executive agency of the DETR. In Scotland control is the responsibility of the Scottish Environment Protection Agency (SEPA), and most appeals are dealt with by the Scottish Office. In Northern Ireland the Environment and Heritage Service is responsible for controlling water pollution. In 1997, there were 4,717 cases in England and Wales of discharges exceeding their consented limits, including a number of offences by water companies discharging insufficiently treated sewage. The majority of these breaches did not cause any significant environmental damage. However, the Environment Agency did bring 65 cases to court, of which 61 were successful, resulting in fines ranging from ￡ 440 to ￡ 12,000 and one prison sentence of two months. In Scotland, there were 2,734 pollution incidents in 1997; SEPA seeks prosecution in all significant cases. In 1997 and 1998, the Government introduced statutory Environmental Quality Standards (EQSs) for 33 substances in water. The new regulations give legal force for the first time to standards for some of the most dangerous pollutants found in the aquatic environment. In the UK, 96 percent of the population live in properties connected to a sewer, and sewage treatment works serve over 80 percent of the population. In England and Wales, the water industry is committed to an investment programme of some ￡ 11,000 million over ten years for improvements to water quality. Progressively higher treatment standards for industrial waste effluents and new measures to combat pollution from agriculture are expected to bring further improvements in water quality. In Scotland, responsibility for the provision of all water and sewerage services lies with three Water and Sewerage Authorities, covering the north, east and west of the country.
考题
单选题Which of the following is a disadvantage of living in a cosmopolitan city, according to the passage?A
The pollution.B
The traffic congestion.C
The high cost of living.D
The population decrease.
考题
问答题练习15 (1) Whatever its underlying reason, there is no doubt that much of the pollution caused could be controlled if only companies, individuals and governments would make more efforts. In the home there is an obvious need to control litter and waste. Food comes wrapped up three or four times in packages that all have to be disposed of; drinks are increasingly sold in bottles or tins which cannot be reused. (2) This not only causes a litter problem, but also is a great process by persuading many of us not only to buy things we neither want nor need, but also to throw away much of what we do buy. Pollution and waste combine to a problem everyone can help to solve by cutting out necessary buying, excess consumption and careless disposal of the products we use in our daily lives.
考题
单选题When a sudden increase in steam demand comes to normal, the drum pressure will and water level in the drum will（）.A
rise, rise alsoB
rise, dropC
drop, riseD
drop, drop also
考题
问答题Pollution is a problem because man, in an increasingly populated and industrialized world, is upsetting the environment in which he lives. Many scientists maintain that one of man’s greatest errors has been to equate growth with advancement. Now “growth” industries are being looked on with suspicion in case their side effects damage the environment and disrupt the relationship of different forms of life. The growing population makes increasing demands on the world’s fixed supply of air, water and land. This rise in population is accompanied by the desire of more and more people for a better standard of living. Thus still greater demands for electricity, water and goods result in an ever increasing amount of waste material to be disposed of.The problem has been causing increasing concern to living things and their environment. Many believe that man is not solving these problems quickly enough and that his selfish pursuit of possessions takes him past the point of no return before be fully appreciates the damage.
考题
问答题Pollution and Ecocrisis The problem of pollution is also of great social concern. Continued population increase, accompanied by a rise in the level of living standards, not only threatens to exhaust American resources but pollutes the environment to such an extent that production in the thickly settled area is impossible without damaging the health of the local residents. Smog, once an urban annoyance, is now recognized as a health risk, and the automobile has been pinpointed as the principal culprit. Heavy industries have been blamed for river, soil, air, noise and visual pollutions. DDT and other chemical remedies have been doing more ecological harm than the good that they may have brought along. Several decades ago, Americans dumped raw sewage into rivers and many industrial plants are now still dumping chemical pollutants into lakes, rivers and oceans. Oceans used to be and are still being considered to be a reserve of seafood. Today, after the oceans have become the home of all pollutants, this use of the oceans is being reduced at an alarming rate. The worst pollution threat is concentrated in and near large cities. There the people-made pollutants increasingly surpass the ability of air and water to dilute (冲淡；稀释) the contaminants (污染物) to safe levels. The natural ecological cycle depends on plants, which absorb some pollutants and release oxygen to the air. But near large cities, natural vegetation becomes scarce, and introduced trees, ornamental shrubs and gardens are far from adequate in absorbing motor vehicle and industrial air pollutants. Finally, some pollutants, most notably atomic waste, may continue to contaminate air, land, and water for thousands of years. Therefore, ecocrisis—ecocatastrophe or ecocide—has been for some time one of the major concerns of not only the ecoactivists and environmentalists, but of many scientists of other fields and the government authorities of many countries as well. Last but not least, there is the question of whether the people will eventually be able to solve all these problems. The American continent is a wealthy land inhabited by many able and well- educated people. There today, people have originated a life-style which is known to the world as being characteristic of a society of consumption—a life-style based on the prodigal (挥霍浪费的) use of material goods. They are using up many times their share of the earth’s resources at a rate unparalleled in history. And I am sorry to say that this life-style of American has been copied by the people of many developed countries, leading to the greatest problem of the modem world as a whole. So I must ask: Are the Americans apt enough to cooperate with other peoples to prevent over-population, resource exhaustion, the catastrophe of pollution and the wanton waste of wealth — problems which are basic to the solution of many outstanding economic, social and political problems? Only time will tell.
考题
问答题Practice 8 A report published recently brings bad news about air pollution. It suggests that it could be as damaging to our health as exposure to the radiation from the 1986 Ukraine nuclear power plant disaster. The report was published by the UK’s Royal Commission on Environmental Pollution. But what can city people do to reduce exposure to air pollution? Quite a lot, it turns out. Avoid walking in busy streets. Choose side streets and parks instead. Pollution levels can fall a considerable amount just by moving a few meters away from the main pollution source—exhaust fumes (废气) . Also don’t walk behind smokers. Walk on the windward (顶风的) side of the street where exposure to pollutants (污染物) can be 50 percent less than on the downwind (顺风的) side. Sitting on the driver’s side of a bus can increase your exposure by 10%, compared with sitting on the side nearest the pavement. Sitting upstairs on a double-decker (双层电车) can reduce exposure. It is difficult to say whether traveling on an underground train is better or worse than taking the bus. Air pollution on underground trains tend to be less toxic (有毒的) than that at street level, coz underground pollution is mostly make up of tiny iron particles (粒子) thrown up by wheels hitting the rails. But diesel (柴油机) and petrol fumes have a mixture of pollutants. when you are crossing a road, stand well back from the curb (路缘) while you wait for the light to change. Every meter really does count when you are close to traffic. As the traffic begins to move, fumes can be reduced in just a few seconds. So holding your breath for just a moment can make a difference, even though it might sound silly. There are large sudden pollution increases during rush hours. Pollution levels fall during nighttime. The time of year also makes a big difference. Pollution levels tend to be at their lowest during spring and autumn when winds are freshest. Extreme cold or hot weather has a trapping effect and tends to cause a build-up of pollutants.
考题
单选题One reason for quick population increase in underdeveloped countries is that ______.A
those countries encourage people to have large familiesB
people can get government support if they have more kidsC
improved public health standards have reduced death rate greatlyD
those countries have enough resources to support a large population
考题
问答题Practice 4 The problem of pollution is also of great social concern. Continued population increase, accompanied by a rise in the level of living standards, not only threatens to exhaust American resources but pollutes the environment to such an extent that production in the thickly settled area is impossible without damaging the health of the local residents. Smog, once an urban annoyance, is now recognized as a health risk, and the automobile has been pinpointed as the principal culprit. Heavy industries have been blamed for river, soil, air, noise and visual pollutions. DDT and other chemical remedies have been doing more ecological harm than the good that they may have brought along. Several decades ago, Americans dumped raw sewage into rivers and many industrial plants are now still dumping chemical pollutants into lakes, rivers and oceans. Oceans used to be and are still being considered to be a reserve of seafood. Today, after the oceans have become the home of all pollutants, this use of the oceans is being reduced at an alarming rate. The worst pollution threat is concentrated in and near large cities. There the people-made pollutants increasingly surpass the ability of air and water to dilute (冲淡；稀释) the contaminants (污染物) to safe levels. The natural ecological cycle depends on plants, which absorb some pollutants and release oxygen to the air. But near large cities, natural vegetation becomes scarce, and introduced trees, ornamental shrubs and gardens are far from adequate in absorbing motor vehicle and industrial air pollutants. Finally, some pollutants, most notably atomic waste, may continue to contaminate air, land, and water for thousands of years. Therefore, ecocrisis—ecocatastrophe or ecocide—has been for some time one of the major concerns of not only the ecoactivists and environmentalists, but of many scientists of other fields and the government authorities of many countries as well.
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