In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list (A、B、C、D、E、F、G……) to fit into each of the numbered blank. There are several extra choices, which do not fit in any of the gaps. (10 points) At the end of the fifteenth century, celestial navigation was just being developed in Europe, primarily by the Portuguese. Prior to the development of celestial navigation, sailors navigated by "deduced"(or "dead") reckoning, hereafter called DR. This was the method used by Columbus and most other sailors of his era. In DR, the navigator finds his position by measuring the course and distance he has sailed from some known point. Starting from a known point, such as a port, the navigator measures out his course and distance from that point on a chart, pricking the chart with a pin to mark the new position. Each day"s ending position would be the starting point for the next day"s course-and-distance measurement. (41)______. The ship"s speed was measured by throwing a piece of flotsam over the side of the ship. There were two marks on the ship"s rail a measured distance apart. When the flotsam passed the forward mark, the pilot would start a quick chant, and when it passed the aft mark, the pilot would stop chanting. The pilot would note the last syllable reached in the chant, and he had a mnemonic that would convert that syllable into a speed in miles per hour. This method would not work when the ship was moving very slowly, since the chant would nm to the end before the flotsam had reached the aft mark. (42)______. Columbus was the first sailor (that we know of) who kept a detailed log of his voyages, but only the log of the first voyage survives in any detail. It is by these records that we know how Columbus navigated, and how we know that he was primarily a DR navigator. (43)______. If Columbus had been a celestial navigator, we would expect to see continuous records of celestial observations; but Columbus"s log does not show such records during either of the transatlantic portions of the first voyage. It has been supposed by some scholars that Columbus was a celestial navigator anyway, and was using unrecorded celestial checks on his latitude as he sailed west on his first voyage. (44)______. In other words, if Columbus were a celestial navigator, we would expect to see a sense of small intermittent course corrections in order to stay at a celestially determined latitude. These corrections should occur about every three or four days, perhaps more often. But that is not what the log shows. (45)______. Only three times does Columbus depart from this course: once because of contrary winds, and twice to chase false signs of land southwest. In none of these cases does he show any desire to return to a celestially-determined latitude. This argument is a killer for the celestial hypothesis.A. Since DR is dependent upon continuous measurements of course and distance sailed, we should expect that any log kept by a DR navigator would have these records; and this is exactly what Columbus"s log looks like.B. On his return voyage in 1493, Columbus started from Samaria Bay on the north coast of Hispaniola, and he made landfall at Santa Maria Island in the Azores. We know his entire DR courses and distances between these two points, since they"re recorded in his log.C. In order for this method to work, the navigator needs a way to measure his course, and a way to measure the distance sailed. Course was measured by a magnetic compass. Distance was determined by a time and speed calculation: the navigator multiplied the speed of the vessel (in miles per hour) by the time traveled to get the distance.D. On the first voyage westbound, Columbus sticks doggedly to his magnetic westward course for weeks at a time.E. Could Columbus has corrected his compasses by checking them against the stars and thus avoids the need for course corrections? This would have been possible in theory, but we know that Columbus could not have actually done this.F. Speed (and distance) was measured every hour. The officer of the watch would keep track of the speed and course sailed every hour by using a peg-board with holes radiating from the center along every point of the compass. The peg was moved from the center along the course traveled, for the distance made during that hour. After four hours, another peg was used to represent the distance made good in leagues during the whole watch. At the end of the day, the total distance and course for the day was transferred to the chart.G. In that case, as magnetic variation pulled his course southward from true west, he would have noticed the discrepancy from his celestial observations, and he would have corrected it.

These are dark days for the book business. Borders, a once-huge bookseller,【C1】______on July 18th that it will close down its remaining stores,【C2】______nearly 10,700 staff jobless. Publishers will lose a showcase for their books,【C3】______could mean more laid-off editors.【C4】______the problem is not the【C5】______: writers will still scribble for scraps.【C6】______demand: American book publishers reported【C7】______across all platforms last year. It is just that no one is making money. The business needs fresh ideas.【C8】______Unbound, a British effort to "crowd-fund" books. Visitors to its website can【C9】______money for a book that is only part-written.【C10】______enough money is raised, the author can【C11】______to finish it—and the pledgers will get a copy. Having launched in May, the firm announced its first【C12】______on July 18th. Terry Jones, of Monty Python fame, has【C13】______the funds to finish a book of quirky stories. Handsome edited volumes and e-books will follow. "We can make books work at a much lower level of【C14】______," explains John Mitchin-son, who co-founded Unbound. Visitors can【C15】______￡10 for an e-book and a nod in the afterword, or up to ￡250 for such【C16】______as lunch with the author. Over 3,000 pledges have come in, averaging ￡30 apieca Authors see a new way to nurture fans and make money,【C17】______publishing budgets dwindle. Readers【C18】______enjoy feeling like part of the【C19】______process. Most readers won't pay ￡8.99 for an acclaimed book, yet some will spend ￡50 on a signed unwritten one. In these digitally isolating times, the personal touch may【C20】______.

Water Problem

As Gilbert White, Darwin, and others observed long ago, all species appear to have the innate capacity to increase their numbers from generation to generation.【F1】 The task for ecologists is to untangle the environmental and biological factors that hold this intrinsic capacity for population growth in check over the long run. The great variety of dynamic behaviors exhibited by different population makes this task more difficult: some populations remain roughly constant from year to year; others exhibit regular cycles of abundance and scarcity; still others vary wildly, with outbreaks and crashes that are in some cases plainly correlated with the weather, and in other cases not. To impose some order on this kaleidoscope of patterns, one school of thought proposes dividing populations into two groups. These ecologists posit that the relatively steady populations have density-dependent growth parameters; that is, rates of birth, death, and migration which depend strongly on population density.【F2】 The highly varying populations have density-independent growth parameters, with vital rates buffeted by environmental events; these rates fluctuate in a way that is wholly independent of population density. This dichotomy has its uses, but it can cause problems if taken too literally. For one thing, no population can be driven entirely by density-independent factors all the time. No matter how severely or unpredictably birth, death, and migration rates may be fluctuating around their long-term averages, if there were no density-dependent effects, the population would, in the long run, either increase or decrease without bound(barring a miracle by which gains and losses canceled exactly).【F3】 Put another way, it may be that on average 99 percent of all deaths in a population arise from density-independent causes, and only one percent from factors varying with density. The factors making up the one percent may seem unimportant, and their cause may be correspondingly hard to determine. Yet, whether recognized or not, they will usually determine the long-term average population density. In order to understand the nature of the ecologist's investigation, we may think of the density-dependent effects on growth parameters as the signal ecologists are trying to isolate and interpret, one that tends to make the population increase from relatively low values or decrease from relatively high ones, while the density-independent effects act to produce noise in the population dynamics.【F4】 For populations that remain relatively constant, or that oscillate around repeated cycles, the signal can be fairly easily characterized and its effects described, even though the causative biological mechanism may remain unknown. 【F5】 For irregularly fluctuating populations, we are likely to have too few observations to have any hope of extracting the signal from the overwhelming noise. But it now seems clear that all populations are regulated by a mixture of density-dependent and density-independent effects in varying proportions.

Finally, other people may give us instrumental support—financial aid, material resources, and needed services—that reduces stress by helping us resolve and cope with our problems.

Now and again I have had horrible dreams, but not enough of them to make me Jose my delight in dreams. To begin with, I like the idea of dreaming, of going to bed and lying still and then, by some queer magic, wandering into another kind of existence. I could never understand why grown-ups took dreaming so calmly when they could make such a fuss about any holiday. This still puzzles me. I am mystified by people who say they never dream and appear to have no interest in the subject. It is much more astonishing than if they said they never went out for a walk. Most people—or at least most Western Europeans—do not seem to accept dreaming as part of their lives. They appear to see it as an annoying little habit, like sneezing or yawning. I have never understood this. My dream life does not seem as important as my waking life only because there is far less of it, but to me it is important. As if there were at least two extra continents added to the world, and lightning excursions running to them at any moment between midnight and breakfast. Then again, the dream life, though queer and confusing and unsatisfactory in many respects, has its own advantages. The dead are there, smiling and talking. The past is there, some-times all broken and confused but occasionally as fresh as a daisy. And perhaps, the future is there too, waving at us. This dream life is often overshadowed by huge mysterious anxieties, with luggage that cannot be packed and trains that refuse to be caught; and both persons and scenes there are not as dependable and solid as they are in waking life, so that Brown and Smith merge into one person while Robinson splits into two, and there are thick woods outside the bathroom door and the dining-room is somehow part of a theater balcony; and there are moments of sorrow or terror in the dream world that are worse than anything else we have known under the sun. Yet this other life has its interests, its enjoyments, its satisfactions, and, at certain rare intervals, a peaceful glow or a sudden excitement, like glimpses of another form of existence altogether, that we cannot match with open eyes.

The Greatest Invention in the Past Century

Anecdotal evidence has long held that creativity in artists and writers can be associated with living in foreign parts. Rudyard Kipling, Pablo Picasso, Ernest Hemingway, Paul Gauguin, Samuel Beckett and others spent years dwelling abroad. Now a pair of psychologists has proved that there is indeed a link. As they report in the Journal of Personality and Social Psychology, WilliamMaddux of INSEAD, a business school in Fontainebleau, France, and Adam Galinsky, of the Kellogg School of Management in Chicago, presented 155 American business students and 55 foreign ones studying in America with a test used by psychologists as a measure of creativity. Given a candle, some matches and a box of drawing pins, the students were asked to attach the candle to a cardboard wall so that no wax would drip on the floor when the candle was lit. (The solution is to use the box as a candleholder and fix it to the wall with the pins.) They found 60% of students who were either living abroad or had spent some time doing so, solved the problem, whereas only 42% of those who had not lived abroad did so. A follow-up study with 72 Americans and 36 foreigners explored their creative negotiating skills. Pairs of students were asked to play the role of a seller of a petrol station who then needed to get a job and a buyer who would need to hire staff to run the business. The two were likely to reach a deadlock because the buyer had been told he could not afford what the seller was told was his minimum price. Nevertheless, where both negotiators had lived abroad 70% struck a deal in which the seller was offered a management job at the petrol station in return for a lower asking price. When neither of the negotiators had lived abroad, none was able to reach a deal. To check that they had not merely discovered that creative people are more likely to choose to live abroad, Dr Maddux and Dr Galinsky identified and measured personality traits, such as openness to new experiences, that are known to predict creativity. They then used statistical controls to filter out such factors. Even after that had been done, the statistical relationship between living abroad and creativity remained, indicating that it is something from the experience of living in foreign parts that helps foster creativity. Merely travelling abroad, however, was not enough. You do have to live there. Packing your beach towel and suntan lotion will not, by itself, make you Hemingway.

Many factors distort the way we interpret the world. Social scientists use the term attribution to describe the process of attaching meaning to behavior. We attribute meaning to both our own actions and to the actions of others, but we often use different yardsticks. Research has uncovered several perceptual errors that can lead to inaccurate attributions. 1. We are influenced by what is most obvious The error of being influenced by what is most obvious is understandable. The most obvious factor is not necessarily the only cause—or the most significant one. 2. We cling to first impressions, even if wrong Labeling people according to our first impressions is an inevitable part of the perception process, problems arise, however, when the labels we attach are inaccurate:once we form an image we tend to hang onto it and make any conflicting information fit our image. Given the almost unavoidable tendency to form first impressions, the best advice we can give is to keep an open mind and to be willing to change your opinion as events prove it mistaken. 3. We tend to assume others are similar to us People with low self-esteem imagine others view them unfavorable, whereas people who like themselves imagine that others like them, too. The frequently mistaken assumption that others'views are similar to our own applies in a wide range of situations. 4. We tend to favor negative impressions of others over positive ones Researches shows that when people are aware of both the positive and negative characteristics of another, they tend to be more influenced by the undesirable traits. 5. We blame innocent victims for their misfortunes The blame we assign for misfortune depends on who the victim is. When others suffer, we often blame the problem on their personal qualities. On the other hand, when we're the victims, we find explanations outside ourselves. Don't misunderstand: We don't always commit the kind of perceptual errors described above. Nonetheless, a large amount of research has proved again and again that our perceptions of others are often distorted in the ways listed above. The moral, then, clear: Don't assume that your first judgment of a person is accurate. [A]Since looking good is so often a personal goal, putting others down can be a cheap way to boost our own self-esteem, stating in effect , 'Tm better than he is." [B]For example, you might blame an unhappy working situation on the boss, overlooking other factors beyond her control such as a change in the economy, the policy of higher management, or demands of customers of other workers. [C]In one study, for example, researchers found that job interviewers were likely to reject candidates who revealed negative information even when the total amount of information highly positive. [D]A boss may think of herself as an excellent manager because her assistants shower her with false praise in order to keep their jobs or gain promotions. Likewise, a child's inflated ego may be based on the praise of doting parents. [E]You've heard a slightly raunchy joke that is pretty funny. You might assume that it won't offend a somewhat straight friend. It does. You might have found out the other person' s real position by asking directly or by checking with others. [F]Suppose, for instance, you mention the name of your new neighbor to a friend. "Oh, I know him, " your friend replies. "He seems nice at first but it's all an act." Perhaps this appraisal is off-base. The neigh bor may have changed since your friend knew him, or perhaps your friend's judgment is simply unfair. Whether the judgment is accurate or not, once you accept your friend's evaluation, it will probably influence the way you respond to the neighbor.

Last week, you got to know that Zhang Hong, one of your middle school classmates, was admitted to Cambridge University as a post-graduate. Write a letter to Zhang, telling her your congratulations, stating your feeling(s), and make a wish. Write your letter with no less than 100 words and write it neatly. Do not sign your own name at the end of the letter; use "Li Ming" instead. You do not need to write the address.

"THE SERVANT"(1963)is one of those films that it is impossible to forget. The servant exploits his master's weaknesses until he turns the tables: the story ends with the a cringing master ministering to a lordly servant. It is hard to watch it today without thinking of another awkward relationship—the one between business folk and their smartphones. Smart devices are sometimes empowering. They put a world of information at our fingertips. But for most people the servant has become the master. Not long ago only doctors were on call all the time. Now everybody is. Bosses think nothing of invading their employees' free time. Work invades the home far more than domestic chores invade the office. Hyperconnectivity exaggerates the decline of certainty and the general cult of flexibility. Smartphones make it easier for managers to change their minds at the last moment. Employees find it ever harder to distinguish between "on-time" and "off-time"—and indeed between real work and make-work. None of this is good for businesspeople' s marriages or mental health. It may be bad for business, too. When bosses change their minds at the last minute, it is hard to plan for the future. How can we reap the benefits of connectivity without becoming its slaves? One solution is digital dieting. Banning browsing before breakfast can reintroduce a small amount of civilization. Banning texting at weekends or, say, on Thursdays, can really show the iPhone who is boss. The problem with this approach is that it works only if you live on a desert island or at the bottom of a lake. Leslie Perlow of Harvard Business School argues that for most people the only way to break the 24/7 habit is to act collectively rather than individually. One of the world's most hard-working organisations, the Boston Consulting Group, introduced rules about when people were expected to be offline, and encouraged them to work together to make this possible. Eventually it forced people to work more productively while reducing burnout. Ms Perlow's advice should be taken seriously. The problem of hyperconnectivity will only get worse, as smartphones become smarter and young digital natives take over the workforce. But ultimately it is up to companies to outsmart the smartphones by insisting that everyone turn them off from time to time.

It may be summertime, but the living isn"t easy—not for weary workers whose last vacation is a distant memory. According to one recent study, 1 in 4 employees in the United States doesn"t get any paid vacation. Almost half don"t take even a week off every year. Economists estimate that the average American works one more month per year today than in 1976. Small-business owners aretaking this daily grind to a whole new level. The number of employers at companies with fewer than 100 workers who plan to take a summer vacation has continued to fall in the past four years. Two in three bosses worry about their businesses when they"re out of the office. Fully 75 percent check in by phone or E-mail even when they"re on "vacation," many of them several times a day. But is all this work good for business? As the last weeks of summer vacation days slip away—yet again, researchers are insisting these extreme jobs have a dark side. All work and no play really can make Jack a dull boy: Apart from health risks that come with overwork, people who don"t get out of the office tend to be less creative, less productive, and, ultimately, less effective. If there is one thing small-business owners can do to improve their companies" performance, experts say, it is taking some time off. There"s a good chance the benefits of vacation will go straight to the bottom line. According to a study by American Express, more than a third of small-business people say their best ideas—the ones that lead to business growth—come not at work but during their downtime. "Having a life outside of work doesn"t detract from work success" but enhances it, a study by the Families and Work Institute concluded in 2005. Happier people, no surprise, tend to be more productive than unhappy people. Two business professors, Sigal Barsade of the University of Pennsylvania"s Wharton School and Donald Gibson of Fairfield University, found in a recent study that employee moods have a measurable effect on just about everything anyone does at work—job performance, decision making, creativity, turnover, teamwork, and leadership. Overwork also comes with serious health risks. Researchers have found that people who work long hours can even become addicted to their own stress hormones. They feel sluggish when they"re out of the office, so they head back for their fix, and the cycle repeats itself. Continuous stress also affects the performance of the part of the brain responsible for memory.

Therehasrecentlybeenadiscussioninthenewspaperontheissueofchoiceofwork.Writeanessaytothenewspaperto1.showyourunderstandingofthesymbolicmeaningofthepicturebelow1)thecontentofthepicture2)themeaning/yourunderstanding2.giveaspecificexample/commentYoushouldneatlywrite160—200words.

The Economist calculates that around the world almost 290 million 15- to 24-year-olds are neither working nor studying: almost a quarter of the planet"s youth. On the other hand, many of the "employed" young have only informal and 【C1】______jobs. In rich countries more than a third, on average, are on temporary【C2】______which make it hard to 【C3】______skills. In poorer ones, according to the World Bank, a fifth are 【C4】______family labourers or work in the informal economy. 【C5】______, nearly half of the world"s young people are either【C6】______the formal economy or contributing less【C7】______than they could. What has caused this【C8】______of joblessness? Young people have long had a raw【C9】______in the labour market. Two things make the problem more【C10】______now. The financial crisis and its consequence had an unusually big【C11】______on them. Many employers【C12】______the newest hires first, so a【C13】______raises youth joblessness disproportionately. Second, the emerging economies that have the largest and fastest-growing【C14】______of young people also have the【C15】______labour markets. Almost half of the world"s young people live in South Asia, the Middle East and Africa. They also have the highest【C16】______of young people out of work or in the informal sector. In rich countries with generous welfare states this【C17】______a heavy burden on taxpayers. One estimate suggests that, in 2011, the economic loss from【C18】______young people in Europe 【C19】______ to $153 billion, or more than 1% of GDP. And failure to employ the young not only【C20】______ growth today. It also threatens it tomorrow.

"The Heart of the Matter," the just-released report by the American Academy of Arts and Sciences(AAAS), deserves praise for affirming the importance of the humanities and social sciences to the prosperity and security of liberal democracy in America. Regrettably, however, the report" s failure to address the true nature of the crisis facing liberal education may cause more harm than good. In 2010, leading congressional Democrats and Republicans sent letters to the AAAS asking that it identify actions that could be taken by "federal, state and local governments, universities, foundations, educators, individual benefactors and others" to "maintain national excellence in humanities and social scientific scholarship and education." In response, the American Academy formed the Commission on the Humanities and Social Sciences. Among the commission"s 51 members are top-tier-university presidents, scholars, lawyers, judges, and business executives, as well as prominent figures from diplomacy, filmmaking, music and journalism. The goals identified in the report are generally admirable. Because representative government presupposes an informed citizenry, the report supports full literacy; stresses the study of history and government, particularly American history and American government; and encourages the use of new digital technologies. To encourage innovation and competition, the report calls for increased investment in research, the crafting of coherent curricula that improve students" ability to solve problems and communicate effectively in the 21st century, increased funding for teachers and the encouragement of scholars to bring their learning to bear on the great challenges of the day. The report also advocates greater study of foreign languages, international affairs and the expansion of study abroad programs. Unfortunately, despite 1%. years in the making, "The Heart of the Matter" never gets to the heart of the matter: the illiberal nature of liberal education at our leading colleges and universities. The commission ignores that for several decades America"s colleges and universities have produced graduates who don"t know the content and character of liberal education and are thus deprived of its benefits. Sadly, the spirit of inquiry once at home on campus has been replaced by the use of the humanities and social sciences as vehicles for publicizing "progressive," or left-liberal propaganda. Today, professors routinely treat the progressive interpretation of history and progressive public policy as the proper subject of study while portraying conservative or classical liberal ideas—such as free markets, self-reliance—as falling outside the boundaries of routine, and sometimes legitimate, intellectual investigation. The AAAS displays great enthusiasm for liberal education. Yet its report may well set back reform by obscuring the depth and breadth of the challenge that Congress asked it to illuminate.

You are supposed to invite Dr. King to make a speech about the future development of computer science at the annual conference of your department. Write a letter to Mr. King to 1) invite him on behalf of your department, 2) tell him the time and place of the conference, 3) promise to give him further details later. You should write about 100 words. Do not sign your own name at the end of the letter. Use "El Ming" instead. You do not need to write the address.

Retailers are looking at bigger sales numbers for digital television sets this Christmas sea son, boosting the spirits of federal regulators and the industry. Government and industry analysts alike have worried that this nation of TV viewers is shifting its gaze too slowly to digital from old-fashioned analog sets. Yet almost 7 million digital television, or DTV, sets will be sold this year, according to the Consumer Electronics Association, a trade group for manufacturers and retailers. Roughly 3 million of these sets will be sold during the last three months of the year. Independent groups also predict a big sales spike. Homes in the United States will have 12.1 million high-definition or HDTV sets—the most sophisticated form of DTV sets—by the end of the year, compared with 7 million at the end of 2003, according to the Yankee Group, a Boston technology research outfit. HDTVs have accounted for the vast majority of about 13 million digital televisions sold since the fall of 1998. "The numbers are very encouraging. We believe consumers are embracing this technology," says Jenny Miller, the Consumer Electronics Association"s spokeswoman. A boost in sales of digital televisions will be welcome news for major retailers anxiously watching the Christmas shopping season that began yesterday. Many national retailers lured customers into their stores with extra-early hours and deep discounts. DTV sets still sell behind traditional analog sets. Almost 22 million analog sets are expected to be sold this year, outpacing even the rosiest predictions for DTV sales. Until recently, consumers who wanted to buy DTV experienced sticker shock. When the sets first reached the market in the late 1990s, they cost several thousand dollars, turning off many consumers. Now, prices for basic DTV sets generally start at about $500. HDTV sets offer the best-quality picture and sound and can cost as much as $15,000, according to Consumer Reports, published by the nonprofit Consumers Union advocacy group. "You"re talking about a couple of hundred dollars at the very least, unless you go for a flat panel or plasma screen, in which case you"re talking thousands of dollars," says Aditya Kishore, senior analyst for the Yankee Group. In addition to falling prices, analysts credit the sales boost for DTV to an increase in the number of programs broadcast in digitally compatible "high definition" as well as a government-led consumer education campaign.

Global warming is already cutting substantially into potential crop yields in some countries—to such an extent that it may be a factor in the food price【C1】______that have caused worldwide stress in recent years, researchers suggest in a new study. Wheat yields in recent years were down by more than 10 percent in Russia and by a few percentage points【C2】______in India, France and China compared with【C3】______they probably would have been without rising【C4】______, according to the study. Corn yields were【C5】______a few percentage points in China, Brazil and France from what would have been【C6】______said the researchers, whose findings were published in Friday's【C7】______of the journal Science. Some countries saw small gains from the temperature increases, however. And in all countries, the【C8】______carbon dioxide that humans are【C9】______into the air acted as a【C10】______that encouraged plant growth,【C11】______some of the losses from rising temperatures caused by that same greenhouse gas. 【C12】______, the study's authors found that when the gains in some countries were weighed【C13】______the losses in other countries, the overall global【C14】______of climate change has been small so far losses of a few percentage points for wheat and corn from what they would have been【C15】______climate change. The general impact on production of rice and soybeans was【C16】______, with gains in some regions entirely counterbalancing losses in others. 【C17】______the authors of the study pointed out that temperature increases were expected to【C18】______in coming decades, making it likely that the challenges【C19】______food production will grow in a era when demand is expected to【C20】______sharply.

In the past few decades, remarkable findings have been made in ethology, the study of animal social behavior. Earlier scientists had【B1】______that nonhuman social life was almost totally instinctive or fixed by genetics. Much more careful observation has shown that 【B2】______ variation occurs among the social ties of most species, showing that learning is a part of social life. That is, the【B3】______are not solely fixed by the genes. 【B4】______, the learning that occurs is often at an early age in a process that is called imprinting. Imprinting is clearly 【B5】______ instinctive, but it is not quite like the learning of humans; it is something in between the two. An illustration best【B6】______the nature of imprinting. Once, biologists thought that ducklings followed the mother duck because of instincts. Now we know that, shortly 【B7】______ they hatch, ducklings fix 【B8】______ any object about the size of a duck and will henceforth follow it. So ducklings may follow a basketball or a briefcase if these are 【B9】______ for the mother duck at the time when imprinting occurs. Thus, social ties can be considerably【B10】______, even ones that have a considerable base【B11】______by genetics. Even among the social insects something like imprinting【B12】______influence social behavior. For example, biologists once thought bees communicated with others purely【B13】______instinct. But, in examining a "dance" that bees do to indicate the distance and direction of a pollen source, observers found that bees raised in isolation could not communicate effectively. At a higher level, the genetic base seems to be much more for an all purpose learning rather than the more specific responses of imprinting. Chimpanzees, for instance, generally【B14】______very good mother but Jane Goodall reports that some chimps carry the infant upside down or【B15】______fail to nurture the young. She believes that these females were the youngest or the 【B16】______ child of a mother. In such circumstances, they did not have the opportunity to observe how their own mother【B17】______for her young. Certainly adolescent chimps who are still with their mothers when other young are born take much interest in the rearing of their young brother or sister. They have an excellent opportunity to learn, and the social ties that are created between mother and young 【B18】______ Goodall to describe the social unit as a family. The mother offspring tie is beyond 【B19】______; there is some evidence to 【B20】______ that ties also continue between siblings of the same sex, that is "brother-brother" and "sister-sister".

Human-induced climate change is likely to make many parts of the world uninhabitable, or at least uneconomic. Over the course of a few decades, if not sooner hundreds of millions of people may be compelled to relocate because of environmental pressures. To a significant extent, water will be the most important determinant of these population movements. Dramatic alterations in the relation between water and society will be widespread, as emphasized in the new report from Working Group II of the Intergovernmental Panel on Climate Change. These shifts may include rising sea levels, stronger tropical cyclones, the loss of soil moisture under higher temperatures, more intense precipitation and flooding, more frequent droughts, the melting of glaciers and the changing seasonality of snowmelt. Impacts will vary widely across the world. It will be important to keep our eye on at least four zones: low-lying coastal settlements, farm regions dependent on rivers fed by snowmelt and glacier melt, sub humid and arid regions, and humid areas in Southeast Asia vulnerable to changes in monsoon patterns. A significant rise in sea levels, even by a fraction of a meter could ruin tens or even hundreds of millions of people. One study found that although coastal areas less than 10 meters above sea level constitute only 2 percent of the world"s land, they contain 10 percent of its population. These coastal zones are vulnerable to storm surges and increased intensity of tropical cyclones—call it the New Orleans Effect. Regions much farther inland will wither. Hundreds of millions of people, including many of the poorest farm households, live in river valleys where irrigation is fed by melting glaciers and snow. The annual snowmelt is coming earlier every year, synchronizing it less and less well with the summer growing season, and the glaciers are disappearing altogether. Thus, the vast numbers of farmers in the Indo-Gangetic Plain will most likely face severe disruptions in water availability. Until now, the climate debate has focused on the basic science and the costs and benefits of reducing greenhouse gas emissions. Attention will now increasingly turn to the urgent challenge of adapting to the changes and helping those who are most affected. Some hard-hit places will be rescued by better infrastructure that protects against storm surges or economizes on water for agriculture. Others will shift successfully from agriculture to industry and services. Yet some places will be unable to adjust altogether, and suffering populations will most likely move. We are just beginning to understand these phenomena in quantitative terms. Economists, hydrologists, agronomists and climatologists will have to join forces to take the next steps in scientific understanding of this human crisis.