Continue to Protect or Destroy Ecosystem Biosphere II was a spectacular failure. The gleaming glass-and-concrete habitat sprawling across the desert in Oracle, Arizona, was supposed to support eight human “biospherians“ for two years. But the seal has to be broken before the experiment ended in 1993. Oxygen had fallen to levels normally seen at an elevation of 17,500 feet. Nitrous oxide had risen to the point where it threatened to cause brain damage. The fresh water supply became contaminated, and vines smothered(厚厚地覆盖)food plants. Insect pollinators(传授花粉的生物)and many other species became extinct. By the end, Biosphere II was overrun with swarms of ants and cockroaches. Scientists who gathered recently to review the Biosphere II experiment reached a disturbing conclusion: “No one yet knows how to engineer systems that provide humans with the life-supporting services that natural ecosystems produce for free.“ The problem is that these ecosystems are undergoing wrenching changes. Water and air quality, while improving in some regions, are deteriorating in many others. Carbon dioxide levels in the atmosphere arc climbing. The world’s population could reach 10 billion by 2050. And famed Harvard biologist Edward O. Wilson says the current rate of species losses puts us “in the midst of one of the great extinction spasms(突然迸发)of geological history.“ All of which makes many ecologists wonder whether humans too will soon become extinct. It’s an incredibly important but incredibly difficult question. If we continue on this course, we’re heading for a world in which we will have to engineer services we’ve always received for free from nature. That’s why the failure of Biosphere II was so disturbing: it proves that we don’t yet know how to do that. The Biosphere II experience demonstrated that maintaining human life is a tricky proposition-especially if we can no longer rely on the services provided by natural ecosystems. If we are currently living through a mass extinction, as Wilson believes, we should consider the past. In the great Permian extinction 245 million years ago, 96 percent of species perished. Eventually, the Earth was repopulated with a rich collection of new species, but it took 100 million years. “That should give pause to anyone who believes that what Homo sapiens(现代人)destroys, nature will redeem, “ Wilson says. “Maybe so, but not within any length of time that has meaning for contemporary humanity.“

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Genocide Many people feel that human beings are responsible for the disappearance of some other animal species. While we may have hastened the disappearance of some, abundant evidence suggests mankind has had little impact. Biologists point out that 50 species can be expected to disappear in the twentieth century but also remind us that about 50 species can be expected in the nineteenth century, and 50 species in each of the centuries before that. Dr. T. H. Jukes at the University of California has pointed out that about UK)million animal species have become extinct since life began on Earth about 3 billion years ago. Thus, animals come and animals go as a natural consequence of something Mr. Darwin discovered. The human race is a recent newcomer to the scene, so we’ve had nothing whatsoever to do with the disappearance of millions of species. In fact, when it comes right down to it, we’re a miserable failure at genocide(种族灭绝). In spite of an all-out centuries-old war on rats, we haven’t made a dent in their numbers, much less extinguished a single species. And in spite of all our high technology we haven’t been successful in eliminating a single undesirable insect species! A friend of mine owns most of the Douglas DC-7 aircrafts left in the world. They make excellent spray planes because they can carry a lot of insecticide and fly for a very long time over great distances. Last year, his company sprayed most of the western Sahara and the Sahel regions of Africa to hold down the locusts and grasshoppers. This year, the environmentalists put pressure on the U.N. to stop it because dieldrin and malathion might cause an increase in the cancer risk of people in the western Sahara and the Sahel. As a result, the hoppers and locusts are back by the zillions and the crops are failing. But the people of West Africa certainly aren’t going to worry about dying of cancer; they are dying of starvation instead. I’ve come to the conclusion that the people who are trying to save the world are probably quite sincere about it but they don’t know much about science and certainly nothing about systems engineering.

Continue to Protect or Destroy Ecosystem Biosphere II was a spectacular failure. The gleaming glass-and-concrete habitat sprawling across the desert in Oracle, Arizona, was supposed to support eight human “biospherians“ for two years. But the seal has to be broken before the experiment ended in 1993. Oxygen had fallen to levels normally seen at an elevation of 17,500 feet. Nitrous oxide had risen to the point where it threatened to cause brain damage. The fresh water supply became contaminated, and vines smothered(厚厚地覆盖)food plants. Insect pollinators(传授花粉的生物)and many other species became extinct. By the end, Biosphere II was overrun with swarms of ants and cockroaches. Scientists who gathered recently to review the Biosphere II experiment reached a disturbing conclusion: “No one yet knows how to engineer systems that provide humans with the life-supporting services that natural ecosystems produce for free.“ The problem is that these ecosystems are undergoing wrenching changes. Water and air quality, while improving in some regions, are deteriorating in many others. Carbon dioxide levels in the atmosphere arc climbing. The world’s population could reach 10 billion by 2050. And famed Harvard biologist Edward O. Wilson says the current rate of species losses puts us “in the midst of one of the great extinction spasms(突然迸发)of geological history.“ All of which makes many ecologists wonder whether humans too will soon become extinct. It’s an incredibly important but incredibly difficult question. If we continue on this course, we’re heading for a world in which we will have to engineer services we’ve always received for free from nature. That’s why the failure of Biosphere II was so disturbing: it proves that we don’t yet know how to do that. The Biosphere II experience demonstrated that maintaining human life is a tricky proposition-especially if we can no longer rely on the services provided by natural ecosystems. If we are currently living through a mass extinction, as Wilson believes, we should consider the past. In the great Permian extinction 245 million years ago, 96 percent of species perished. Eventually, the Earth was repopulated with a rich collection of new species, but it took 100 million years. “That should give pause to anyone who believes that what Homo sapiens(现代人)destroys, nature will redeem, “ Wilson says. “Maybe so, but not within any length of time that has meaning for contemporary humanity.“

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Practically all animals communicate through sounds. Almost Clearly Absolutely Basically

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The thief was finally captured two miles away from the village. caught killed found jailed

Such a database would be extremely costly to set up. transfer destroy establish update

Electromagnetic Energy White light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy. The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space. Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared(红外线的)radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays(紫外线)and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so mush energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones. Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too. Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed(利用)by man. Chemical energy comes from electron(电子)rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun’s energy comes from the nuclear reactions in which hydrogen is changed into helium(氦). Nuclear energy is beginning to compete with coal as an econpmical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy. A. Nuclear reactions as the lasting source of the sun’s energy B. The most important source of energy C. Types of electromagnetic energy D. The machines used for energy generation E. Seeking new sources of energy F. The use of ultraviolet radiation in medicine

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The two banks have announced plans to merge next year. combine sell close break

New Product Will Save Lives Drinking water that looks clean may still contain bugs(虫子), which can cause illness. A small company called Genera Technologies has produced a testing method in three stages, which shows whether water is safe. The new test shows if water needs chemicals added to it, to destroy anything harmful. It was invented by scientist Dr. Adrian Patton.who started Genera five years ago. He and his employees have developed the test together with a British water company. Andy Headland, Genera’s marketing director, recently presented the test at a conference in the USA and forecast good American sales for it. Genera has already sold 11 of its tests at $42,500 a time in the U.K. and has a further four on order. It expects to sell another 25 tests before the end of March. The company says it is the only test in the U.K. to be approved by the government. Genera was formed five years ago and until October last year had only five employees; it now employs 14. Mr. Headland believes that the company should make around $19 million by the end of the year in the U.K. alone.

A. when it is absorbed by matter B. when it is cloudy C. because they can pass through solid objects D. when the sunrays are fierce E. when a change in the nucleus of an atom takes place F. when electron rearrangement takes place

The seal of the Biosphere II had to be broken before the experiment ended because______.

What is the purpose of the experiment mentioned in this passage?

It is implied that many ecologists______.

Edward O. Wilson believes that the mass extinction happened in the past______.

The message the author wishes to convey in the passage is that______.