What does the speaker mainly discuss?I want to talk today about some studies. They seem to indicate that there is a startling world-wide decline in the number of amphibians, such as frogs, toads and salamanders. There’s little doubt that one reason why the number of amphibians is declining is their habitats have been destroyed when the developers fill in ponds and marshes to build houses. Amphibians can’t just move somewhere. They need water to lay their eggs in. Another problem is the growing fish industry. Another range of popular pool fish such as carp have been introduced to many lakes and ponds all over the world. Raising and selling these fish can be profitable, but the fish eat the eggs and offspring of amphibians that were already living in the lakes and ponds. Other factors could be contributing to the decline include acid rain and the spread of pesticide residues. Many pesticides that farmers added to their crops are eventually washed away by the rain and end up in ponds and other bodies of water where amphibians live. Amphibians are especially vulnerable to pesticides dissolved in the water because of their moist skins. Water can pass through amphibians allowing toxins dissolved in the water to enter the amphibians’ body. The distribution of different species of amphibians. Possible reasons for reduction in the number of amphibians. The effects of environmental change on the fish industry. Guidelines for the responsible use of pesticides.

A = BOOK 1 B = BOOK 2 C = BOOK 3 D = BOOK 4 Which book(s)say(s)that... the climate affects the future sustainable agricultural development? 【P1】______ environmental control is related with the national revenues? 【P2】______ the environmental problems are not caused overnight? 【P3】______ a variety of species are on the decrease? 【P4】______ agriculture is also a factor for the degradation of environment? 【P5】______ pollution can be controlled by increasing the production cost of polluting goods? 【P6】______ pollution control needs the support of technology and techniques? 【P7】______ provides lessons for agriculture, trade, land use and tax policy from an economic perspective? 【P8】______ the degradation of environment causes the change of climate? 【P9】______ the approaches to research should be adjusted to the changing situation? 【P10】______ A BOOK 1 The book offers a comprehensive perspective on the consequences and possible policy solutions for climatic change as we move into the twenty-first century. It assesses the impact of potential feature global climate change on agriculture and the need to sustain agricultural growth for the economic development. The book begins by examining the role of international research institutions in overcoming environmental constraints on sustainable agricultural growth and economic development. The authors then discuss how agricultural research systems may be restructured to respond to global environmental problems such as climate change and loss of genetic diversity. The discussion then extends to consider environmental accounting and indexing, to illustrate how environmental quality can be included formally in measures of national income, social welfare and sustainability. The third part of the book focuses on the effects of and policy responses to climate change. Chapters in this part examine the effect of climate change on production, trade, land use patterns and livelihoods. They consider impacts on the distribution of income between developed and developing countries remain a major economic activity. Authors take on an economy-wide perspective to draw lessons for agriculture, trade, land use and tax policy. B BOOK 2 The ozone layer is threatened by chemical emissions; the climate is endangered from fossil and deforestation , and global biodiversity is being lost by reason of thousands of years of habitat conversions. Global environmental problems arise out of the accumulated impacts from many years’ and many countries’ economic development. In order to address these problems the states of the world must cooperate to manage their development processes together—this is what an international environmental agreement must do. But can the world’ s countries cooperate successfully to manage global development? How should they manage it? Who should pay for the process, as well as for the underlying problems? This book presents an examination of both the problem and the process underlying international environmental lawmaking: the recognition of international interdependence, the negotiation of international agreements and the evolution of international resource management. It examines the general problem of global resource management by means of general principles and case studies and by looking at how and why specific negotiations and agreements have failed to achieve their targets. The book is designed as an introductory text for those studying global environmental policy making and institution building. It will also be of interest to practitioners and policy makers and scholars in the areas of environmental economics and law. C BOOK 3 Industrialization to achieve economic development has resulted in global environmental degradation. While the impacts of industrial activity on the natural environment are a major concern in developed countries, much less is known about these impacts in developing countries. This source book identifies and quantifies the environmental consequences of industrial growth, and provides policy advice, including the use of clean technologies and environmentally sound production techniques, with special reference to the developing world. The developing world is often seen as having a high percentage of heavily polluting activities within its industrial sector. This, combined with a substantial agriculture sector, which contributes to deforestation, the erosion of the top soil and desertification, has led to extreme pressures on the environment and impoverishes the population by destroying its natural resource base. This crisis suggests that sound industrialization policies are of paramount importance in developing countries’ economic development, and calls for the management of natural resources and the adoption of low-waste of environmentally clean technologies. The authors consider the industrial sector as a pollutant to other sectors of the economy, and then focus on some industrial-specific pollutants within the manufacturing sector and some process-specific industrial pollutants. They conclude by reviewing the economic implications of promoting environmentally sound industrial development, specially adressing the question of the conflict or complementarily which may exist between environmental goods and industrial production. D BOOK 4 This is an important book which presents new concepts of the marginal cost of substituting non-pollutive for pollutive goods. Technically in its approach it complements the other literature in the field and will be a significant contribution to the understanding of microeconomic issues in pollution control. The book focuses on the three main concepts; substitutions in consumption, emission abatement and exposure avoidance. The first part considers the adjustment of the scope and combination of goods produced as a method for controlling pollution. The author argues that pollution is controlled by increasing the relative price of the polluting goods in the production process, thereby reducing demand and subsequent production of the goods. In the second part, the discussion is extended to include the possibilities of preventing or abating emissions in relation to three models: first, pollution prevention when non-polluting inputs and processes are substituted for pollutants; second, when a proportion of the polluting output is recycled rather than being discarded; and finally end-of-pipe abatement where additional technology is used. In conclusion, the author assesses the extent to which pollution damage is controlled by avoidance of emissions, with avoidance being modeled as an add-on technology with its own returns to scale.

Some people claim that television is good for children because it gets children cleverer by watching it, while others think that television is bad for children. Write an article to express your point of view on this topic. You should write no less than 250 words. Write your article on ANSWER SHEET 2.

The recent social and economic changes in the US have great impact on all the American housing system.In recent years, there have been great social and economic changes in the United States. And, these changes have affected almost all of America’s housing system, from home building to home buying. First of all, American families are becoming smaller. People nowadays are having fewer children, or choosing not to have children at all. Many people are marrying later in life. And about 40% of all American marriages end in divorce. All this means that many Americans now want smaller houses. And a large percentage are buying apartments. This has created a shortage of rental housing in many parts of the country. It has caused special difficulties for those who are old or poor, and do not have the money to buy a place of their own. Some people are solving this problem by forming cooperatives. In a cooperative , everyone in an apartment building joins together and buys a share of the building. If 20% of those living in the cooperative have low earnings, then the group can get a low-interest loan from the government. If people want to sell their share in the cooperative, they can not earn more than they paid for it. This helps keep the cost of cooperatives low. Recent concern over the cost of energy also has brought changes in American housing. Some people are moving back to the cities, to save the cost of driving long distances to work. And, many Americans have begun to look for homes that cost almost nothing to heat, because the temperature of the earth changes very little as the season changes. Other new houses get their energy from the sun. During the day, heat from sunlight is collected through windows on the south side of the house. At night, the windows are covered, and the collected warmth heats the home. Recently, the American economy has also had a major effect on American housing. Inflation has pushed the cost of homes higher and higher. And, interest rates have become very high. Buyers now must pay as much as 18 percent interest for housing loans. Americans with just moderate earnings now find it very difficult to make monthly payments on a new home. In the last few months, even apartments have grown too expensive for most people to buy. These developments have brought about a crisis in America’s housing industry. Officials say that homes now are selling only half as fast as they do in a good year. Many home building companies are closing. And unemployment in that industry is now more than 16 percent much higher than in most other American industries. Officials in the housing industry have taken some steps to end this crisis. Banks are permitting people to make lower monthly payments when they move into new houses. Then they increase the payments at a later time. Some builders are helping buyers pay the high interest rates on their mortgages. Builders say they are not earning any money this way. But, they say at least they are surviving. Builders are also looking for ways to put together houses at a lower cost. One way is to build as much of the house as possible in a factory. Some houses—called mobile homesites are made completely in factories, then transported to the buyer. TRUE FALSE

According to the speaker, what are convenience goods?In the field of marketing, consumer goods are classed according to the way in which they are purchased. The two main categories are convenience goods and shopping goods. Two lesser types are specialty goods and unsought goods. People do not spend much time shopping for convenience items such as groceries, newspapers, toothpaste, razor blades, aspirin, and candy. The buying of convenience goods may be done routinely, as some families buy groceries once a week. Such regularly purchased items are called staples. Sometimes convenience products are bought on impulse, for example, someone has a sudden desire for an ice cream sundae on a hot day. Or they may be purchased as emergency items. Shopping goods are items for which customers search. They compare prices, quality, and styles, and may visit a number of stores before making decisions. Buying an automobile is often done this way. Shopping goods fall into two classes: those that are perceived as basically the same and those that are regarded as different. Items that are looked upon as basically the same include such things as home appliances, television sets, and automobiles. Having decided on the model desired, the customer is primarily interested in getting the item at the most favorable price. Items regarded as inherently different include clothing, furniture, and dishes. Quality , style and fashion will either take precedence over price, or they will not matter at all. Specialty goods have characteristics that impel customers to make special efforts to find them. Price may be no consideration at all. Specialty goods can include almost any kind of product. Normally, specialty goods have a brand name or other distinguishing characteristics. Unsought goods are items a consumer does not necessarily want or need or may not even know about. Promotion or advertising brings such goods to the consumer’s attention. The product could be something new on the market or it may be a fairly standard service, such as life insurance, for which most people will usually not bother shopping. Commodities that people are in constant need of. Goods that are convenient to use or purchase. Items that people tend to buy under impulse. Items that have to be bought once a week.

How many planets are there in the solar system revolving around the sun?Earth is one of nine planets which revolve(绕转)around the sun. This family of planets, with their moons, is known as the solar system. Since we live on Earth, we think it is the most important planet. But the other planets are also interesting. Some are smaller than Earth, some larger;some are hotter , some colder. Each one is different from all the others and has something special about it. No one knows for certain how the solar system began. We do know a lot about the planets, however, from the science of astronomy(天文学). Astronomers have done research on the planets and other objects in space for thousands of years. Astronomy is a very complicated science. We look at the other planets to study them, but the planet we are on is moving all the time. Computers have helped us in the past twenty or thirty years. The satellites we sent into space to measure and take pictures also tell a lot a-bout the planets and help us to understand them. Mercury(水星)is the closest planet to the sun. It is also the smallest and fastest planet. The speed of the planet gave it its name: Mercury was the rapid messenger of the Roman gods. Mercury completes its orbit around the sun in only 88 days, while Earth’s orbit takes 365 — days. A day on Mercury, however, is much longer than a day on Earth. Earth rotates on its axis once every 24 hours. Mercury rotates on its axis once every 59 days. Venus(金星)is the second planet in distance from the sun. It is about the same size as Earth, and it comes closer to Earth than any other planets. Next to the sun and the moon, Venus is the easiest object in the sky to see. People of ancient times loved its brightness and beauty so much that they named it after the Roman goddess of love and beauty. Venus revolves around the sun once every 225 days and rotates on its axis once every 224 days. Information from telescopes and satellites shows us that the planet is very hot. The temperature is usually between 300 and 675 degrees Celsius. We can observe both Venus and Mercury either in the evening or early in the morning just before the sun rises. Mars(火星)is called the red planet because of its definite(明确的)red-orange color. It is the fourth farthest planet from the sun. A day on Mars is only about 40 minutes longer than a day on Earth, but a year lasts 687 days. The planet was named after the Roman god of war. For many years, people believed that there was life on Mars, but we now know that there probably isn’t. The Mariner space program sent many satellites to Mars. We have excellent photos and information on this neighbor planet, and nothing suggests that there is any life there. The fifth planet from the sun is also the largest of all the planets, Jupiter(木星). Jupiter revolves around the sun once every 12 years, yet its day is amazingly(惊人地)short. Its rotation, or its day, is only about 10 hours long. This is the fastest rotation—the shortest day—of any of the planets. The planet’s name is appropriate, since Jupiter was the largest Roman god—the king of all the other gods. If you can imagine Jupiter as a hollow ball, all of the other planets would fit inside and there would still be a lot of room left. Jupiter has fourteen moons, the largest number of any planets.

“Down-to-earth“ means someone or something that is honest, realistic and easy to deal with. It is a pleasure to find【C1】______who is down-to-earth. A person who is down-to-earth is easy to talk【C2】______and accepts other people as equals. A down-to-earth person is just the【C3】______of someone who acts important or proud. Down-to-earth persons may be【C4】______members of society, of course. But they do not let their importance “【C5】______to their heads“. They do not consider themselves to be better persons than【C6】______of less importance. Someone who is filled with his own importance and pride, 【C7】______without cause, is said to have “his nose in the air“. There is【C8】______way a person with his nose in the air can be down-to-earth. Americans【C9】______another expression that means almost the same as “down-to-earth“. The expression is “both-feet-on-the-ground“. Someone【C10】______both-feet-on-the-ground is a person with a good understanding【C11】______reality. He has what is called “ common sense, “ he may have dreams, 【C12】______he does not allow them to block his knowledge of【C13】______is real. The opposite kind of【C14】______is one who has his “head-in-the-clouds“. A man with his head-in-the-clouds is a dreamer【C15】______mind is not in the real world. 【C16】______, such a dreamer can be brought back to earth. Sharp words from teacher can usually【C17】______a day-dreaming student down-to-earth. Usually, the person who is down-to-earth is very【C18】______ to have both feet on the ground.【C19】______we have both our feet on the ground, when we are down-to-earth, we act honestly and openly【C20】______others. Our lives are like the ground below us, solid and strong.

Shortages of flu vaccine are nothing new in America, but this year’ s is a whopper. Until last week, it appeared that 100 million Americans would have access to flu shots this fall. Then British authorities, concerned about quality-control problems at a production plant in Liverpool, barred all further shipments by the Chiron Corp. Overnight, the U. S. vaccine supply dwindled by nearly half and federal health officials found themselves making an unusual plea. Instead of beseeching us all to get vaccinated, they’ re now urging most healthy people between the ages of 2 and 64 not to. “This reemphasizes the fragility of our vaccine supply, “ says Dr. Martin Myers of the National Network for Immunization Information, “ and the lack of redundancy in our system. “ Why is such a basic health service so easily knocked out? Mainly because private companies have had little incentive to pursue it. To create a single dose of flu vaccine, a manufacturer has to grow live virus in a 2-week-old fertilized chicken egg, then crack the egg, harvest the virus and extract the proteins used to provoke an immune response. Profit margins are narrow, demand is fickle and, because each year’ s flu virus is different, any leftover vaccine goes to waste. As a result, the United States now has only two major suppliers(Chiron and Aventis Pasteur)—and when one of them runs into trouble, there isn’ t much the other can do about it. “ A vaccine maker can’ t just call up and order 40 million more fertilized eggs, “ says Manon Cox, of Connecticut-based Protein Sciences Corp. “There’ s a whole industry that’ s scheduled to produce a certain number of eggs at a certain time. “ Sleeker technologies are now in the works, and experts are hoping that this year’ s fiasco will speed the pace of innovation. The main challenge is to shift production from eggs into cell cultures—a medium already used to make most other vaccines. Flu vaccines are harder than most to produce this way, but several biotech companies are now pursuing this strategy, and one culture-based product(Solvay Pharmaceuticals’ Invivac)has been cleared for marketing in Europe. For Americans, the immediate challenge is to make the most of a limited supply. The government estimates that 95 million people still qualify for shots under the voluntary restrictions announced last week. That’ s nearly twice the number of doses that clinics will have on hand, but only 60 million Americans seek out shots in a normal year. In fact, many experts are hoping the shortage will serve as an awareness campaign—encouraging the people who really need a flu shot to get one.

Not long ago, a mysterious Christmas card dropped through our mail slot. The envelope was addressed to a man named Raoul, who, I was relatively certain, did not live with us. The envelope wasn’ t sealed, so I opened it. The inside of the card was blank. Ed, my husband, explained that the card was both from and to the newspaper de-liveryman. His name was apparently Raoul, and Raoul wanted a holiday tip. We were meant to put a check inside the card and then drop the envelope in the mail. When your services are rendered at 4 a. m. , you can’t simply hang around, like a hotel bellboy expecting a tip. You have to be direct. So I wrote a nice holiday greeting to this man who, in my imagination, fires The New York Times from his bike aimed at our front door, causing more noise with mere newsprint than most people manage with sophisticated black market fireworks. With a start, I realized that perhaps the reason for the 4 a. m. —wake-up noise was not ordinary rudeness but carefully executed spite: I had not tipped Raoul in Christmases past. I honestly hadn’ t realized I was supposed to. This was the first time he’d used the card tactic. So I got out my checkbook. Somewhere along the line, holiday tipping went from an optional thank-you for a year of services to a Mafia-style protection racket(收取保护费的黑社会组织). Several days later, I was bringing our garbage bins back from the curb when I noticed an envelope taped to one of the lids. The outside of the envelope said MICKEY. It had to be another tip request, this time from our garbage collector. Unlike Raoul, Mickey hadn’t enclosed his own Christmas card from me. In a way, I appreciated the directness. “I know you don’t care how merry my Christmas is, and that’ s fine, “ the gesture said. “I want $30, or I’ 11 ’ forget’ to empty your garbage bin some hot summer day. I put a check in the envelope and taped it back to the bin. The next morning, Ed noticed that the envelope was gone, though the trash hadn’t yet been picked up: “Someone stole Mickey’ s tip!“ Ed was quite certain. He made me call the bank and cancel the check. But Ed had been wrong. Two weeks later, Mickey left a letter from the bank on our steps. The letter informed Mickey that the check, which he had tried to cash, had been cancelled. The following Tuesday morning, when Ed saw a truck outside, he ran out with his wallet. “Are you Mickey?“ The man looked at him with scorn. “Mickey is the garbageman. I am the recycling. “ Not only had Ed insulted this man by hinting that he was a garbageman, but he had obviously neglected to tip him. Ed ran back inside for more funds. Then he noticed that the driver of the truck had been watching the whole transaction. He peeled off another twenty and looked around, waving bills in the air. “Anyone else?“ Had we consulted the website of the Emily Post Institute, this embarrassing breach of etiquette(礼节)could have been avoided. Under “trash/recycling collectors“ in the institute’ s Holiday Tipping Guidelines, it says, “ $ 10 to $30 each. “ You may or may not wish to know that your pet groomer, hairdresser, mailman and UPS guy all expect a holiday tip.

According to the American Academy of Dermatology, an estimated 10 to 50 million people in this country have an allergic reaction to poison ivy each year. Poison ivy is often very difficult to spot. It closely resembles several other common garden plants, and can also blend in with other plants and weeds. But if you come into contact with it, you’ 11 soon know by the itchy, blistery rash that forms on your skin. Poison ivy is a red, itchy rash caused by the plant that bears its name. Many people get it when they are hiking or working in their garden and accidentally come into direct contact with the plant’ s leaves, roots, or stems. The poison ivy rash often looks like red lines, and sometimes it forms blisters. 【R1】______ About 85 percent of people are allergic to the urushiol in poison ivy, according to the American Academy of Dermatology. Only a tiny amount of this chemical—1 billionth of a gram—is enough to cause a rash in many people. Some people may boast that they’ ve been exposed to poison ivy many times and have never gotten the rash, but that doesn’t necessarily mean they’ re not allergic. Sometimes the allergy doesn’ t emerge until you’ ve been exposed several times, and some people develop a rash after their very first exposure. It may take up to ten days for the rash to emerge the first time. 【R2】______ Here are some other ways to identify the poison ivy plant. It generally grows in a cluster of low, weed-like plants or a woody vine which can climb trees or fences. It is most often found in moist areas, such as riverbanks, woods, and pastures. The edges of the leaves are generally smooth or have tiny “teeth“. Their color changes based on the season—reddish in the spring; green in the summer; and yellow, orange, or red in the fall. Its berries are typically white. 【R3】______ The body’ s immune system is normally in the business of protecting us from bacteria, viruses, and the foreign invaders that can make us sick. But when urushiol from the poison ivy plant touches the skin, it instigates an immune response, called dermatitis, to what would otherwise be a harmless substance. Hay fever is another example of this type of response; in the case of hay fever, the immune system overreacts to pollen, or another plant-produced substance. 【R4】______ The allergic reaction to poison ivy is known as delayed hypersensitivity. Unlike immediate hypersensitivity, which causes an allergic reaction within minutes of exposure to an antigen, delayed hypersensitivity reactions don’ t emerge for several hours or even days after the exposure. 【R5】______ In the places where your skin has come into contact with poison ivy leaves or urushiol, within one to two days you’ll develop a rash, which will usually itch, redden, burn, swell, and form blisters. The rash should go away within a week, but it can last longer. The severity of the reaction often has to do with how much urushiol you’ ve touched. The rash may appear sooner in some parts of the body than in others, but it doesn’t spread—the urushiol simply absorbs into the skin at different rates in different parts of the body. Thicker skin such as the skin on the soles of your feet, is harder to penetrate than thinner skin on your arms and legs. A. Because urushiol is found in all parts of the poison ivy plant—the leaves, stems, and roots—it’ s best to a-void the plant entirely to prevent a rash. The trouble is, poison ivy grows almost everywhere in the United States(with the exception of the Southwest, Alaska, and Hawaii), so geography won’ t help you. The general rule to identify poison ivy, “leaflets three, let it be, “ doesn’t always apply. Poison ivy usually does grow in groups of three leaves, with a longer middle leaf—but it can also grow with up to nine leaves in a group. B. Most people don’t have a reaction the first time they touch poison ivy, but develop an allergic reaction after repeated exposure. Everyone has a different sensitivity, and therefore a slightly different reaction, to poison ivy. Sensitivity usually decreases with age and with repeat exposures to the plant. C. Here’ s how the poison ivy response occurs. Urushiol makes its way down through the skin, where it is metabolized, or broken down. Immune cells called T lymphocytes(or T-cells)recognize the urushiol derivatives as a foreign substance, or antigen. They send out inflammatory signals called cytokines, which bring in white blood cells. Under orders from the cytokines, these white blood cells turn into macrophages. The macrophages eat foreign substances, but in doing so they also damage normal tissue, resulting in the skin inflammation that occurs with poison ivy. D. Poison ivy’ s cousins, poison oak and poison sumac, each have their own unique appearance. Poison oak grows as a shrub(one to six feet tall). It is typically found along the West Coast and in the South, in dry areas such fields, woodlands, and thickets. Like poison ivy, the leaves of poison oak are usually clustered in groups of three. They tend to be thick, green, and hairy on both sides. Poison sumac mainly grows in moist, swampy areas in the Northeast, Midwest, and along the Mississippi River. It is a woody shrub made up of stems with rows of seven to thirteen smooth-edged leaflets. E. The culprit behind the rash is a chemical in the sap of poison ivy plants called urushiol. Its name comes from the Japanese word “ urushi, “ meaning lacquer. Urushiol is the same substance that triggers an allergic reaction when people touch poison oak and poison sumac plants. Poison ivy, Eastern poison oak, Western poison oak, and poison sumac are all members of the same family—Anacardiaceae. F. Call your doctor if you experience these more serious reactions: Pus around the rash(which could indicate an infection). A rash around your mouth, eyes, or genital area. A fever above 100 degrees. A rash that does not heal after a week.

What does the man do?W: Do you enjoy your work? Do you enjoy meeting people? M: Yes. Sometimes. I’ve got to be honest. Sometimes. W: So, some people you like and some you don’t? M: Yeah, it’s like a lot of things, meeting the general public. You get good days, and you get bad days. But I do enjoy the job. I like the freedom of the job, being self-employed. W: Do you ever get difficult passengers? M: Yes, sometimes. W: What sort of things do they get up to? M: I would say sometimes a lot of difficult passengers are people who don’t go in cabs a lot and they’re unfamiliar with procedures, especially if you work nights. People drinking or the extras that would be included on the tariff after a certain time of night. W: You mean they argue with you over money? M: Yes, that can happen. Or the way... the good thing is , people can argue about the way that you go on a certain route because they always know better. But nine times out of ten the route that they take you on is far longer so, you know, they’re the eventual losers. W: So if you do have a difficult passenger you want to get rid of, what do you do? M: I’d stop the cab and tell them to get out. W: Does that often happen? M: Mmm, it’s happened to me three times. And they’ve got out. So I, I myself haven’t had a lot of problems with difficult people, you know. W: When you pick up tourists as passengers, what kind of places do they like to go to? M: I suppose the most famous landmark is Buckingham Palace, the Tower of London, maybe Harrods;but certainly Buckingham Palace. A taxi-driver. A bus driver. A policeman. A tourist guide.

What does the speaker mainly discuss?I want to talk today about some studies. They seem to indicate that there is a startling world-wide decline in the number of amphibians, such as frogs, toads and salamanders. There’s little doubt that one reason why the number of amphibians is declining is their habitats have been destroyed when the developers fill in ponds and marshes to build houses. Amphibians can’t just move somewhere. They need water to lay their eggs in. Another problem is the growing fish industry. Another range of popular pool fish such as carp have been introduced to many lakes and ponds all over the world. Raising and selling these fish can be profitable, but the fish eat the eggs and offspring of amphibians that were already living in the lakes and ponds. Other factors could be contributing to the decline include acid rain and the spread of pesticide residues. Many pesticides that farmers added to their crops are eventually washed away by the rain and end up in ponds and other bodies of water where amphibians live. Amphibians are especially vulnerable to pesticides dissolved in the water because of their moist skins. Water can pass through amphibians allowing toxins dissolved in the water to enter the amphibians’ body. The distribution of different species of amphibians. Possible reasons for reduction in the number of amphibians. The effects of environmental change on the fish industry. Guidelines for the responsible use of pesticides.

At 18, Ashanthi DeSilva of suburban Cleveland is a living symbol of one of the great intellectual achievements of the 20th century. Bom with an extremely rare and usually fatal disorder that left her without a functioning immune system(the “bubble-boy disease“ , named after an earlier victim who was kept alive for years in a sterile plastic tent), she was treated beginning in 1990 with a revolutionary new therapy that sought to correct the defect at its very source, in the genes of her white blood cells. It worked. Although her last gene-therapy treatment was in 1992, she is completely healthy with normal immune function, according to one of the doctors who treated her, W. French Anderson of the University of Southern California. Researchers have long dreamed of treating diseases from hemophilia to cancer by replacing mutant genes with normal ones. And the dreaming may continue for decades more. “There will be a gene-based treatment for essentially every disease, “ Anderson says, “within 50 years. “ It’ s not entirely clear why medicine has been so slow to build on Anderson’ s early success. The National Institutes of Health budget office estimates it will spend $ 432 million on gene-therapy research in 2005, and there is no shortage of promising leads. The therapeutic genes are usually delivered through viruses that don’t cause human disease. “The virus is sort of like a Trojan horse, “ says Ronald Crystal of New York Presbyterian/Weill Cornell Medical College. “The cargo is the gene. At the University of Pennsylvania’ s Abramson Cancer Center, immunologist Carl June recently treated HIV patients with a gene intended to help their cells resist the infection. At Cornell University, researchers are pursuing gene-based therapies for Parkinson’ s disease and a rare hereditary disorder that destroys children’ s brain cells. At Stanford University and the Children’ s Hospital of Philadelphia, researchers are trying to figure out how to help patients with hemophilia who today must inject themselves with expensive clotting drugs for life. Animal experiments have shown great promise. But somehow, things get lost in the translation from laboratory to patient. In human trials of the hemophilia treatment, patients show a response at first, but it fades over time. And the field has still not recovered from the setback it suffered in 1999, when Jesse Gelsinger, an 18-year-old with a rare metabolic disorder, died after receiving an experimental gene therapy at the University of Pennsylvania. Some experts worry that the field will be tarnished further if the next people to benefit are not patients but athletes seeking an edge. This summer, researchers at the Salk Institute in San Diego said they had created a “marathon mouse“ by implanting a gene that enhances running a-bility; already, officials at the World Anti-Doping Agency are preparing to test athletes for signs of “gene doping“. But the principle is the same, whether you’ re trying to help a healthy runner run faster or allow a muscular-dystrophy patient to walk. “Everybody recognizes that gene therapy is a very good idea, “ says Crystal. “And eventually it’ s going to work.

According to the speaker, how do developers contribute to the reduction of amphibian population?

According to the speaker, how do some pesticides get into ponds?

According to the speaker, why do pesticides pose a threat to amphibians?