问答题为什么名义工资对于总需求的变动无法做出迅速的调整?对这一事实的解释使经济学家提出了不同于长期总供给曲线的短期总供给曲线，请应用总供求模型说明货币只是在长期才是中性的。

问答题设有经济模型Y=C+I+G，I=20+0.15Y，C=40+0.65Y，G=60 试求：

问答题试述供给学派关于边际税率的三个基本命题及其政策主张。

问答题某国的宏观经济模型为：试求财政支出为G=50，货币政策为时的国民收入水平Y、利率水平r、消费C、投资I、货币交易需求L1、货币投机需求L2。

问答题资本深化与资本宽化

问答题设名义利率是如此之低，以致持有货币的机会成本是可忽略的。设由于人们对有关其财富在货币与其他资产之间的分配无所谓，并且在无任何利率改变的条件下，他们因此愿意改变其货币持有量。

单选题Egyptian wine has an extensive history within the history of Egyptian civilization. Grapes were not (1) to the landscape of Egypt, rather the vines themselves are (2) to have been imported from the Phoenicians, (3) the actual origins remain in (4) . What is known, is that (5) the third millennium BC, Egyptian kings of the first (6) had extensive wine cellars, and wine was used extensively in the temple ceremonies. The main (7) of wine in Egypt, took place between the king, nobles, and the priests in temple ceremonies, and is (8) by numerous painted relief's, and other (9) evidence. The vineyards of ancient Egypt, were quite different from the modern methods of wine making today. (10) viticulture ( or wine making), ceased to (11) an exclusively ceremonial purpose, the Egyptians began to experiment with simple structures for their vines to train on, (12) found a way to train their vines so they were easy low (13) bushes, and found ways for the soil to (14) more moisture for the vines. Egyptian wine making experiments included the use of different wine presses, adding heat to the must ( the grape juice ready for fermentation) (15) make the wine sweet, and differences in vat types and materials. The (16) finished product of wine, was poured through a cloth filter, and then into earthenware jars, (17) they would be sealed with natural tar and left to (18) . The Egyptians kept accurate records of their vintages, and (19) of their wines, each jar of wine was clearly (20) with it's own vintage, and quality.

单选题Current Group, a Germantown-based technology firm, has taken over an ordinary looking house in Bethesda and turned it into a laboratory for smart-grid technology, the system the company believes will bring the nation's electricity grids into the digital age. In the front yard stands a utility pole hooked up to a special transformer that connects the power lines to high-speed Internet. Hundreds of sensors attached to the lines monitor how power flows through the home. That information is then sent back to the utility company. The process lets a utility more efficiently manage the distribution of electricity by allowing two-way communication between consumers and energy suppliers via the broadband network on the power lines. Based on data they receive from hundreds of homes, utilities can monitor usage and adjust output and pricing in response to demand. Consumers can be rewarded with reduced rates by cutting back on consumption during peak periods. And computerized substations can talk to each other so overloaded circuits hand off electricity to those that have not fully loaded, helping to prevent blackouts. Some utility companies have launched initiatives to give consumers data about their energy consumption habits in an effort to lower energy bills. Smart-grid technology takes such programs further by automating electricity distribution, which would make grids more reliable and efficient. By partnering with utilities, the company hopes to tap into $4.5 billion in stimulus grants intended to encourage smart-grid development. When he announced the funding, President Obama pointed to a project in Boulder, Colo. , as an example of a successful smart-grid experiment. Current is one of the companies working on the project. Current's chief executive Tom Casey believes the technology will help utility companies better distribute electricity produced by renewable resources, such as solar panels or wind farms. " A smart grid's system can be paired up with the renewable resources so that when the renewable source is varying, the overall load can be varied as well, " Casey told the House Select Committee on Energy Independence and Global Warming. " This will reduce or eliminate the need for backup coal or gas-based power generation plants. /

单选题Since the 1930s, the idea that creatures might advertise their " fitness " as mates through symmetry has been around. It rests on the notion that factors ranging from bad genes to coming off worse in too many fights will lead to asymmetries others can see. And over the past few years, experiments with animals and humans seemed to support the idea that symmetry in features such as plumage and facial characteristics influences mate selection. But no one had actually checked that the animals in these experiments can actually see the subtle differences in symmetry, typically of between 1 and 2 percent. Now the first such experiment has been carried out. The results are worrying for advocates of symmetry detection as a powerful factor in mate selection. John Swaddle, an ethnologist at the University of Bristol, performed the experiment using wild starlings, which have excellent eyesight. He trained them to hit keys marked with bar patterns with varying levels of asymmetry in order to receive food rewards. This showed the starlings could easily detect asymmetries of between 5 and 10 percent. But at between 1 and 2 percent, their performance plummeted to no better than random guessing. " This suggests that the levels of asymmetry that birds encounter in nature will often be just too small to be detected, " says Swaddle. He says experiments that linked small asymmetries to fitness may have produced misleading correlations, and says the only direct evidence that birds use asymmetry as a cue to mate fitness involves levels of asymmetry of at least 10 percent. " I think signaling by asymmetry will probably only occur when species show such very large asymmetries—and this doesn't occur that often. " This raises questions about research suggesting that humans are influenced by visual asymmetry in their choice of partner. Michael Butt of the Perception Laboratory at the University of St. Andrews, who has carried out such experiments, concedes that no one has ever checked if humans have a threshold to asymmetry detection. He thinks a conclusive test of this would probably involve manipulating complex three-dimensional images: " It would be a very difficult experiment to do " Burt adds that the abilities of animals to detect asymmetry in bar patterns may not reflect their talent for spotting asymmetries in body shape. " The visibility of an asymmetry may well depend on its type, " he says. Swaddle agrees, and is planning further experiments. " But I suspect that asymmetry is used as a visual cue less often than most people appear to presume, " he warns.

单选题Many in the Middle East have difficulty in adjusting themselves to the new situation created by the departure of the imperial powers. For the first time in almost 200 years, the rulers and people of the Middle East have to accept the final responsibility for their own affairs, to make their own mistakes and to accept the consequences. This is difficult to internalize, even to perceive, after so long a period. For the entire lifetimes of those who formulate and conduct policy at the present time and of their predecessors for many generations, vital decisions were made elsewhere, ultimate control lay elsewhere, and the principal task of statesmanship and diplomacy was as far as possible to avoid or reduce the dangers of this situation and to exploit such opportunities as it might from time to time offer. It is very difficult to forsake the habits not just of a lifetime but of a whole era of history. The difficulty is much greater when alien cultural, social and economic preeminence continues and even increases, despite the ending of alien political and military domination. Military and to a growing extent political intervention by the West has indeed ended, but the impact of its science and culture, its technology, amenities and institutions remains and even increases. As in other parts of the non-Western world, this impact has been and will be enormous. In these circumstances, it is natural that Middle Easterners should continue to assume—and proceed on the assumption—that real responsibility and decision still lie elsewhere. In its crudest form, this belief leads to wild and strange conspiracy theories directed against those whom they regard as their enemies—Israel, and more generally the Jews, the United States, and more generally the West. No theory is too absurd to be asserted or too preposterous to be widely and instantly believed. Even among more responsible statesmen and analysts, a similar belief in alien power, albeit in a less crude form, often seems to guide both analysis and policy. Some even go so far as to invite outside intervention, presumable in the belief that only outside powers have the capacity to make and enforce decisions. A case in point is the constant appeal to the United States to involve itself in the Arab Israel conflict, oddly coupled with the repeated accusation of "American imperialism. " This state of mind is likely to continue for some time, with appeals for support or even intervention to the United States, to Russia and even to the European Union. In time, no doubt, Middle Eastern governments and people will learn how to use this window of opportunity to the best advantage—that is, of course, if the window remains open long enough.

单选题Florence Nightingale is most remembered as a pioneer of nursing and a reformer of hospital sanitation methods. For most of her ninety years, Nightingale pushed for reform of the British military health-care system and with that the profession of nursing started to gain the respect it deserved. Unknown to many, however, was her use of new techniques, of statistical analysis, such as during the Crimean War when she plotted the incidence of preventable deaths in the military. She developed a method to prevent the needless deaths caused by unsanitary conditions and the need for reform. With her analysis, Florence Nightingale revolutionized the idea that social phenomena could be objectively measured and subjected to mathematical analysis. She was an innovator in the collection, interpretation, and display of statistics. Florence Nightingale's two greatest life achievements-pioneering of nursing and the reform of hospitals-were amazing considering that most Victorian women of her age group did not attend universities or pursue professional careers. It was her father, William Nightingale, who believed women, especially his children, should get an education. So Nightingale and her sister learned Italian, Latin, Greek, history, and mathematics. She in particular received excellent early preparation in mathematics. During Nightingale's time at Scutari, she collected data and systematized record-keeping practices. Nightingale was able to use the data as a tool for improving city and military hospitals. Nightingale's calculations of the death rate showed that with an improvement of sanitary methods, deaths would decrease. In February, 1855, the death rate at the hospital was 42.7 percent of the cases treated. When Nightingale's sanitary reform was implemented, the death rate declined. Nightingale took her statistical data and represented them graphically. As Nightingale demonstrated, statistics provided an organized way of learning and lead to improvements in medical and surgical practices. She also developed a Model Hospital Statistical Form for hospitals to collect and generate consistent data and statistics. She became a Fellow of the Royal Statistical Society in 1858 and an honorary member of the American Statistical Association in 1874. Karl Pearson acknowledged Nightingale as a "prophetess" in the development of applied statistics.

单选题Drug use is rising dramatically among the nation' s youth after a decade of decline. From 1993 to 1994, marijuana use among young people (1) from 12 to 17 jumped 50 percent. One in five high school seniors (2) marijuana daily. Monitoring the Future, which (3) student drug use annually, reports that negative attitudes about drugs have declined for the fourth year in a row. (4) young people see great risk in using drugs. Mood-altering pharmaceutical drugs are (5) new popularity among young people. Ritalin, (6) as a diet pill in the 1970s and now used to (7) hyperactive children, has become a (8) drug on college campuses. A central nervous system (9) , Ritalin can cause strokes, hypertension, and seizures. Rohypnol, produced in Europe as a (10) tranquilizer, lowers inhibitions and suppresses short-term memory, which has led to some women being raped by men they are going out with. (11) taken with alcohol, its effects are greatly (12) . Rock singer Kurt Cobain collapsed from an (13) of Rohypnol and champagne a month before he committed (14) in 1994. In Florida and Texas, Rohypnol has become widely abused among teens, who see the drug as a less expensive (15) for marijuana and LSD. Alcohol and tobacco use is increasing among teenagers, (16) younger adolescents. Each year, more than one million teens become regular smokers, (17) they cannot legally purchase tobacco. By 12th grade, one in three students smokes. In 1995, one in five 14-year-olds reported smoking regularly, a 33 percent jump (18) 1991. Drinking among 14-year-olds climbed 50 percent from 1992 to 1994,and all teens reported substantial increases in (19) drinking. In 1995, one in five 10th graders reported having been drunk in the past 30 days. Two-thirds of high school seniors say they know a (20) with a drinking problem.

单选题One reason many politicians behave badly these days is that we spend less time thinking about what it means to behave well. This was less of a problem in past centuries when leaders, teachers and clergy held detailed debates over what it meant to have good character. In the 18th century, for example, Edmund Burke composed a long, famous passage defining the standards of political excellence. In the 19th century, Anthony Trollope wrote a series of popular novels fussing over what it means to behave well in political life. Trollope's view was different than ours. Many Americans today assume that people are born with a good Inner Self but get corrupted by politics. American voters are always looking for the Innocent Outsider who can come in and bring sweeping change. Trollope admired Prudent Insiders, not Innocent Outsiders. His most admirable characters have been educated by long experience. They have grown mature by exercising responsibility. They have been ennobled by custom and civilization. In his books, powerless outsiders often behave self-indulgently and irresponsibly. Those who are in government have to grapple with the world as it really is. Trollope's ideal politicians—who have names like Plantagenet Palliser, Joshua Monk and the Duke of St. Bungay put service before independence. Their party and their country have asked them to accept certain duties and face certain problems, and they just get on with it. They are more weighty, but also more boring. Trollope's ideal politicians share certain traits. They are reserved, prudent and scrupulous. They immerse themselves in dull practical questions like, say, converting the currency system. They are not sweeping thinkers, but they make sensitive discriminations about the people and the circumstances around them. They learn to operate within the constraints imposed by their idiom, and they don't whine or complain about those constraints. They develop delicate understandings of what is required in a given place in time. Trollope's ideal leaders are not glamorous celebrities of the sort we have come to long for since J. F. Kennedy. They are more like seamen or carpenters. They are judged by their professional craftsmanship. They are thin-skinned about any moral transgression they might commit and rigorously honest when judging themselves. They try to make things better but are acutely aware that everything they do might make things worse. Trollope's leaders don't embrace change quickly but have to be dragged into embracing it after much interrogation, and the change they prefer is incremental. Trollope praises one of his prime ministers, Plantagenet Palliser, for "that exquisite combination of conservatism and progress which is his country's present strength and her best security for the future. " Trollope's readers would have come away from his books with a certain model for how practical people should behave, which they could either copy or argue with. I'm not sure his exemplars could thrive amid the TV politics of today, which calls for grand promises and bold colors. But there are prudent, reserved people in government even now.

单选题Democrats on the Senate Judiciary Committee vented their fury over high gasoline prices at executives of the nation's five largest oil companies on Wednesday, grilling the oilmen over their multimillion-dollar pay packages and warning them that Congress was intent on taking action that could include a new tax on so-called windfall profits. Such showdowns between lawmakers and oil titans have become a familiar routine on Capitol Hill. But with gas prices nearing $ 4 a gallon, and lawmakers headed home for a weeklong Memorial Day recess where they expect to get an earful from angry constituents, there is added urgency for Congress to appear active. But while momentum is building for several measures, including a bill that would allow the Organization of the Petroleum Exporting Countries to be sued in American courts under antitrust laws, there is little sign that any of the proposals would do much, if anything, to lower prices quickly. And the oil executives warned that government intervention might only make things worse. Instead, they called on Congress to allow more drilling and exploration for domestic oil. The increasing urgency to seem aggressive about gasoline prices was apparent on Tuesday when the House voted by an overwhelming 324 to 84 to approve the bill, commonly referred to as NOPEC, which classifies OPEC as a monopoly in violation of the Sherman Antitrust Act. Senate Democrats have included that measure as part of a package of legislation intended to address the high price of gasoline, along with the tax on windfall profits and a measure to tamp down speculation in the oil futures market that many lawmakers think is contributing to the run-up in prices. At the Judiciary Committee hearing, Democratic senators struggled to have the executives explain how oil prices had risen so high. The senators expressed doubt that basic laws of supply and demand were at work and suggested instead a more sinister combination of monopolistic behavior by oil-producing countries, speculation in the futures markets and sheer corporate greed. On Monday, President Bush signed a bill temporarily suspending the purchase of crude oil for the nation's Strategic Petroleum Reserve. Mr. Bush had initially opposed such action but relented after the House and Senate approved the bill by wide margins. Senator Richard J. Durbin, Democrat of Illinois and a strong supporter of Senator Baraek Obama's presidential bid, made a particularly pointed attack, in which he seemed to warn the oil executives that they would soon no longer have such a good friend in the White House. He also suggested that Mr. Bush should be doing more to press the oil companies to help lower prices at the pump, while acknowledging that it would be difficult to pass a windfall profits tax while Mr. Bush was still in office.

单选题Deflation is an economic theory relating changes in the price levels to changes in the quantity of money. In its developed (1) , it constitutes an analysis of the (2) underlying inflation and deflation. As (3) by the English philosopher John Locke in the 17th century, the Scottish (4) David Hume in the 18th century, and (5) , it was a weapon (6) the mercantilists, who were thought to equate wealth with money. If the (7) of money by a nation merely raised (8) , argued the quantity theorists, then a "favourable" balance of trade, (9) desired by mercantilists, would increase the supply of money but would not in-crease (10) . In the 19th century the quantity theory (11) to the ascendancy of free trade over protectionism. In the 19th and 20th centuries it played a part in the (12) of business cycles and in the theory of foreign (13) rates. The (14) theory came under attack during the 1930s, (15) monetary expansion seemed ineffective in combating deflation. Economists argued that the levels of investment and government spending were more important than the money supply in determining economic activity.The tide of opinion (16) again in the 1960s, when experience (17) post-World WarⅡ inflation and new empirical (18) of money and prices— (19) A Monetary History of the United States (1963) by Milton Friedman and Anna Schwartz—restored much of the quantity theory' s lost prestige. One implication of this theory is that the size of the stock of money must be considered when shaping governmental policies (20) to control prices and maintain full employment.

单选题Animal studies are under way, human trial protocols are taking shape and drug makers are on alert. All the international health community needs now is a human vaccine for the bird flu pandemic sweeping a cluster of Asian countries. The race for a vaccine began after the first human case emerged in Hong Kong in 1997. Backed by the World Health Organization (WHO), three research teams in the US and UK are trying to create a seed virus for a new vaccine. Their task is formidable, but researchers remain optimistic." There are obstacles, but most of the obstacles have been treated sensibly," says Richard Webby, a virologist at St. Jude Children's Research Hospital in Memphis, Tennessee. The biggest challenge is likely to be the rapidly mutating virus. Candidate vaccines produced last year against the H5N1 virus are ineffective against this year's strain. Scientists will have to constantly monitor the changes and try to tailor the vaccine as the virus mutates. They can't wait to see which one comes next. The urgency stems from fears that I-ISN1 will combine with a human flu virus, creating a pathogen(病原体) that could be transmitted from person to person. But if people have no immunity to the virus, the strain may not mutate as rapidly in people as it does in birds. To quickly generate the vaccine, researchers are using reverse genetics, which allows them to skip the long process of searching through reassorted viruses for the correct genetic combination. Instead, scientists clone sequences for hemagglutinin(红血球凝聚素) and neuraminidase(神经氨酸苷酶), the two key proteins in the virus. The sequences are then combined with human influenza genes to create a customized reference strain. Because products developed with reverse genetics have never been tested in humans, the candidate vaccines will first have to clear regulatory review. In anticipation, the US Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medicinal Products (EMEA) are both preparing pandemic response plans. The EMEA has produced a fist-track licensing program, an industry task force and detailed guidance for potential applicants. In Europe, a reassortant influenza virus -- but not the inactivated vaccine -- produced by reverse genetics would be considered a genetically modified organism, and manufacturers would need approval from their national or local safety authorities. The WHO has prepared a preliminary biosafety risk assessment of pilot-lot vaccine, which could help speed up the review. A preliminary version of their protocol calls for several hundred subjects, beginning with a group of young adults and gradually expanding to include those most susceptible to the flu -- children and the elderly." If we had product," says Lambert," it would probably be a couple of months at the earliest before we have early data in healthy adults./

单选题Halfway through" The Rebel Sell," the authors pause to make fun of" free-range" chicken. Paying over the odds to ensure that dinner was not, in a previous life, confined to tiny cages is all well and good. But" a free-range chicken is about as plausible as a sun-loving earth-worm": given a choice, chickens prefer to curl up in a nice dark corner of the barn. Only about 15% of" free-range" chickens actually use the space available to them. This is just one case in which Joseph Heath, who teaches philosophy at the University of Toronto, and Andrew Potter, a journalist and researcher based in Montreal, find fault with well-meaning but, in their view, ultimately naive consumers who hope to distance themselves from consumerism by buying their shoes from Mother Jones magazine instead of Nike. Mr Heath and Mr Potter argue that" the counterculture," in all its attempts to be subversive, has done nothing more than create new segments of the market, and thus ends up feeding the very monster of consumerism and conformity it hopes to destroy. In the process, they cover Marx, Freud, the experiments on obedience of Stanley Milgram, the films" Pleasantville"," The Matrix" and "American Beauty", 15th-century table manners, Norman Mailer, the Unabomber, real-estate prices in central Toronto (more than once), the voluntary-simplicity movement and the world's funniest joke. Why range so widely? The authors' beef is with a very small group: left-wing activists who eschew smaller, potentially useful campaigns in favor of grand statements about the hopelessness of consumer culture and the dangers of" selling out". Instead of encouraging useful activities, such as pushing for new legislation, would-be leftists are left to participate in unstructured, pointless demonstrations against" globalization, or buy fair-trade coffee and flee-range chicken, which only substitutes snobbery for activism. Two authors of books that railed against brands, Naomi Klein ("No Logo") and Alissa Quart("Branded"), come in for special derision for diagnosing the problems of consumerism but refusing to offer practical solutions. Anticipating criticism, perhaps, Messrs Heath and Potter make sure to put forth a few of their own solutions, such as the 35-hour working week and school uniforms (to keep teenagers from competing with each other to wear ever-more-expensive clothes). Increasing consumption, they argue throughout, is not imposed upon stupid workers by overbearing companies, but arises as a result of a cultural" arms race": each person buys more to keep his standard of living high relative to his neighbors'. Imposing some restrictions, such as a shorter working week, might not stop the arms race, but it would at least curb its most offensive excesses. (This assumes one finds excess consumption offensive; even the authors do not seem entirely sure.) But on the way to such modest suggestions, the authors want to criticise every aspect of the counterculture, from its disdain, for homogenisation, franchises and brands to its political offshoots. As a result, the book wanders: chapters on uniforms and on the search for" cool" could have been cut. Moreover, the authors make the mistake of assuming that the consumers they sympathise with—the ones who buy brands and live in tract houses—know enough to separate themselves from their purchases, whereas the free-trade-coffee buyers swallow the brand messages whole, as it were. Still,it would be a shame if the book' s ramblings kept it from getting read. When it focuses on explaining how the counterculture grew out of post-World War Ⅱ critiques of modem society, "The Rebel Sell" is a lively read, with enough humour to keep the more theoretical stretches of its argument interesting. At the very least, it puts its finger on a trend: there will be plenty of future critics of capitalism lining up for their free-range chicken.

单选题You know you should do it, other people do it all the time. Maybe you've already done it but it wasn't very satisfying, and you'd like to learn to do it better. I'm talking, of course, about having a business lunch. Don't feel embarrassed if you are uncomfortable with the idea of sitting over a grilled chicken breast, talking to a prospective client. Most inexperienced, overeager launchers believe the main purpose of a business lunch is to either (a) conduct business or (b) eat lunch, and they're unsure how to mix the two. Don't worry! Business lunches aren't about either business or lunch,they're about building relationships. One of my business rules is "People do business with people they like. " Often, it's not products, prices, or the company that makes the sale—it's the person Business lunches are the perfect time for you and your client, supplier, or employee to get to know each other as people. This helps establish common interests and makes working together easier. The single most important thing you can do at a business lunch—even more important than picking up the tab—is listen. You don't need a particular reason to ask someone to lunch, so don't wait until for a certain occasion or issue. Don't make it seem like lunch is going to be a sales call. Instead, try the straightforward approach, "We've been doing business together for almost a year. I'd like to take you to lunch and get to know you a little better." Or a little less straightforward, "I'm often in your area, how about having lunch sometime?" Have the other person suggest a place to eat—"Is there a restaurant you've been wanting to try?" Or if you have a limited budget, you choose a nice mid priced restaurant. Forget McDonald's. If you're thanking someone for an important order, take them to a really special, possibly new, restaurant. If you did the inviting, you pick up the tab, even if your guest says, "I can put this on my company's credit card." But don't have a scene arguing over the check. You can just say, "You can get the next one." Some companies have policies that don't permit employees to be treated; in that case, split the tab.

单选题Despite decades of scientific research, no one yet knows how much damage human activity is doing to the environment. Humans are thought to be responsible for a whole host of environmental problems, ranging from global warning to ozone depletion. What is not in doubt, however, is the devastating effect humans are having on the animal and plant life of the planet. Currently, an estimated 50,000 species become extinct every year. If this carries on, the impact on all living creatures is likely to be profound, says Dr. Nick Middleton, a geographer at Oxford University. " All species depend in some way on each other to survive. And the danger is that, if you remove one species from this very complex web of interrelationships, you have very little idea about the knock-on effects of other extinctions. " Complicating matters is the fact that there are no obvious solutions to the problem. Unlike global warning and ozone depletion—which, if the political will was there, could be reduced by cutting gas emissions—preserving biodiversity remains an intractable problem. The latest idea is " sustainable management " , which is seen as a practical and economical way of protecting species from extinction. This means humans should be able to use any species of animal or plant for their benefit, provided enough individuals of that species are left alive to ensure its continued existence. For instance, instead of depending on largely ineffective laws against poaching, it gives local people a good economic reason to preserve plants and animals. In Zimbabwe, there is a sustainable management project elephants. Foreign tourists pay large sums of money to kill these animals for sport. This money is then given to the inhabitants of the area where the hunting takes place. In theory, locals will be encouraged to protect elephants, instead of poaching them—or allowing others to poach them—because of the economic benefit involved. This sounds like a sensible strategy, but it remains to be seen whether it will work. With corruption endemic in many developing countries, some observers are skeptical that the money will actually reach the people it is intended for．Others wonder how effective the locals will be at stopping poachers. There are also questions about whether sustainable management is practical when it comes to protecting areas of great-bio-diversity such as the world's tropical forests. In theory, the principle should be the same as with elephants—allow logging companies to cut down a certain number of trees, but not so many as to completely destroy the forest. Sustainable management of forests requires controls on the number of trees which are cut down, as well as investment in replacing them. But because almost all tropical forests are located in countries which desperately need revenue from logging, there are few regulations to do this. Moreover, unrestricted logging is so much more profitable that wood prices from managed forests would cost up to five times more—an increase that consumers, no matter how " green " , are unlikely to pay. For these reasons, sustainable management of tropical forests is unlikely to become widespread in the near future. This is disheartening news. It's estimated these forests contain anything from 50 to 90 percent of all animal and plant species on Earth. In one study of a five-square-kilometer area of rain forest in Peru, for instance, scientists counted 1,300 species of butterfly and 600 species of bird. In the entire continental United States, only 400 species of butterfly and 700 species of bird have been recorded. Scientist Professor Norman Myers sees this situation as a gigantic " experiment we're conducting with our planet " . " We don't know what the outcome will be. If we make a mess of it, we can't move to another planet…It's a case of one planet, one experiment. /

单选题What's your earliest childhood memory? Can you remember learning to walk? Or talk? The first time you heard thunder or watched a television program? Adults seldom (1) events much earlier than the year or so before entering school, (2) children younger than three or four (3) retain any specific, personal experiences. A variety of explanations have been (4) by psychologists for this " childhood amnesia " . One argues that the hippocampus, the region of the brain which is (5) for formling memories, does not mature until about the age of two. But the most popular theory (6) that, since adults don't think like children, they cannot (7) childhood memories. Adults think in words, and their life memories are like stories or (8) —one event follows another as in a novel or film. (9) , when they search through their mental (10) for early childhood memories to add to this verbal life story, they don't find any that fit the (11) . It's like trying to find a Chinese word in an English dictionary. Now psychologist Annette Simms of the New York State University offers a new (12) for childhood amnesia. She argues that there simply aren't any early childhood memories to recall. According to Dr. Simms, children need to learn to use someone else's spoken (13) of their personal (14) in order to turn their own short-term, quickly forgotten (15) of them into long-term memories. (16) , children have to talk about their (17) and hear others talk about them—Mother talking about the afternoon (18) looking for seashells at the beach or Dad asking them about their day at Ocean Park. Without this (19) reinforcement, says Dr.Simms, children cannot form (20) memories of their personal experiences.