大学英语六级分类模拟题452_真题-无答案

大学英语六级分类模拟题452 (总分445,考试时间90分钟)

Reading Comprehension

Section A

Why Teenagers Act Crazy

A. Adolescence is practically synonymous in our culture with risk taking, emotional drama and all forms of strange behavior. Until very recently, the widely accepted explanation for adolescent angst has been psychological. Developmentally, teenagers face a number of social and emotional challenges, like starting to separate from their parents, getting accepted into a peer group and figuring out who they really are. It doesn\"t take a psychoanalyst to realize that these are anxiety-provoking transitions.

B. But there is a darker side to adolescence that, until now, was poorly understood: a surge during teenage years in anxiety and fearfulness. Largely because of aquirk(古怪) of brain development, adolescents, on average, experience more anxiety and fear and have a harder time learning how not to be afraid than either children or adults.

C. Different regions and circuits of the brain mature at very different rates. It turns out that the brain circuit for processing fear—theamygdala(杏仁核)—isprecocious(早熟的) and develops way ahead of theprefrontal cortex(前额皮质), the seat of reasoning and executive control. This means that adolescents have a brain that is wired with an enhanced capacity for fear and anxiety, but is relatively underdeveloped when it comes to calm reasoning.

D. You may wonder why, if adolescents have such enhanced capacity for anxiety, they are such novelty seekers and risk takers. It would seem that the two traits are at odds. The answer, in part, is that the brain\"s reward center, just like its fear circuit, matures earlier than the prefrontal cortex. That reward center drives much of teenagers\" risky behavior. This behavioral paradox also helps explain why adolescents are particularly prone to injury and trauma. The top three killers of teenagers are accidents, homicide and suicide. The brain-development lag has huge implications for how we think about anxiety and how we treat it. It suggests that anxious adolescents may not be very responsive to psychotherapy that attempts to teach them to be unafraid, like cognitive behavior therapy, which is zealously prescribed for teenagers.

E. What we have learned should also make us think twice—and then some—about the ever rising use of stimulants in young people, because these drugs may worsen anxiety and make it harder for teenagers to do what they are developmentally supposed to do: Learn to be unafraid when it is appropriate to do so. Of course, most adolescents do not develop anxiety disorders, but acquire the

skill tomodulate(调节) their fear as their prefrontal cortex matures in young adulthood, at around age 25. But up to 20 percent of adolescents in the United States experience a diagnosable anxiety disorder, like generalized anxiety or panic attacks, probably resulting from a mix of genetic factors and environmental influences. The prevalence of anxiety disorders and risky behavior (both of which reflect this developmental disjunction in the brain) have been relatively steady, which suggests to me that the biological contribution is very significant.

F. One of my patients, a 32-year-old man, recalled feeling anxious in social gatherings as a teenager. \"It wasviscerally(出自内心地) unpleasant and I felt as if I couldn\"t even speak the same language as other people in the room,\" he said. It wasn\"t that he disliked **pany; rather, socializing in groups felt dangerous, even though intellectually he knew that wasn\"t the case. He developed a strategy to deal with his discomfort: alcohol. When he drank, he felt relaxed and able to engage. Now treated and sober for several years, he still has a trace of social anxiety and still wishes for a drink in anticipation of socializing.

G. Of course, we all experience anxiety. Among other things, it\"s a normal emotional response to threatening situations. The hallmark of an anxiety disorder is the persistence of anxiety that causes intense distress and interferes with functioning even in safe settings, long after any threat has receded. We\"ve recently learned that adolescents show heightened fear responses and have difficulty learning how not to be afraid. In one study using brain M. R. I., researchers at Weill Cornell Medical College and Stanford University found that when adolescents were shown fearful faces, they had exaggerated responses in the **pared with children and adults.

H. The amygdala is a region buried deep beneath the cortex that is critical in evaluating and responding to fear. it sends and receives connections to our prefrontal cortex alerting us to danger even before we have had time to really think about it. Think of that split-secondadrenaline(肾上腺素) surge when you see what appears to be a snake out on a hike in the woods. That instantaneous fear is your amygdala in action. Then you circle back, take another look and this time your prefrontal cortex tells you it was just a harmless stick. Fear learning lies at the heart of anxiety and anxiety disorders. This primitive form of learning allows us to form associations between events and specific cues and environments that may predict danger. Way back on thesavanna(热带草原), for example, we would have learned that the rustle in the grass or the sudden flight of birds might signal a predator—and taken the cue and run to safety. Without the ability to identify such danger signals, we would have been lunch long ago. But once previously threatening cues or situations become safe, we have to be able to re-evaluate them and suppress our learned fear associations. I. Another patient I saw in consultation recently, a 23-year-old woman, described how she became anxious when she was younger after seeing a commercial aboutasthma(哮喘). \"It made me incredibly worried for no reason, and I had a panic attack soon after seeing it,\" she said. As an older teenager, she became worried about getting too close to homeless people and would hold her breath when near them, knowing that \"this was crazy and made no sense\". B. J. Casey, a professor of psychology and the director of the Sackler Institute at Weill Cornell Medical College, has studied fear learning in a group of children, adolescents and adults. Subjects were shown a colored square at the same time that they were exposed to anaversive(令人反感的) noise. The colored square, previously a neutral stimulus, became associated with an unpleasant sound and elicited a fear response similar to that elicited by the sound.

J. What Dr. Casey and her colleagues found was that there were no differences between the subjects in the acquisition of fear conditioning. But when Dr. Casey trained the subjects to

essentially unlearn the association between the colored square and the noise—a process called fear extinction—something very different happened. With fear extinction, subjects are repeatedly shown the colored square in the absence of the noise. Now the square, also known as the conditioned stimulus, loses its ability to elicit a fear response. Dr. Casey discovered that adolescents had a much harder time \"unlearning\" the link between the colored square and the noise than children or adults did.

K. In effect, adolescents had trouble learning that a cue that was previously linked to something aversive was now neutral and \"safe\". If you consider that adolescence is a time of exploration when young people develop greater autonomy, an enhanced capacity for fear and a more persistent memory for threatening situations are adaptive and would confer survival advantage. In fact, the developmental gap between the amygdala and the prefrontal cortex that is described in humans has been found across mammalian species, suggesting that this is an evolutionary advantage. This new understanding about the neurodevelopmental basis of adolescent anxiety has important implications, too, in how we should treat anxiety disorders. One of the most widely used and empirically supported treatments for anxiety disorders is cognitive behavior therapy, a form of extinction learning in which a stimulus that is experienced as frightening is repeatedly presented in a nonthreatening environment. If, for example, you had a fear of spiders, you would be gradually exposed to them in a setting where there were no dire consequences and you would slowly lose yourarachnophobia(蛛蛛恐惧症). The paradox is that adolescents are at increased risk of anxiety disorders in part because of their impaired ability to successfully extinguish fear associations, yet they may be the least responsive todesensitization(脱敏) treatments like cognitive behavior therapy precisely because of this impairment.

L. But we do know this.. Adolescents are not just carefree novelty seekers and risk takers; they are uniquely vulnerable to anxiety and have a hard time learning to be unafraid of passing dangers. Parents have to realize that adolescent anxiety is to be expected, and to comfort their teenagers—and themselves—by reminding them that they will grow up and out of it soon enough. 1. People suffering from an anxiety disorder tend to have enduring anxious feelings after any threat has faded.

2. For teenagers, the region for reasoning in the brain develops slower than the brain circuit for processing fear and anxiety.

3. That the amygdala and the prefrontal cortex in mammals mature at different speeds is an evolutionary advantage.

4. Alcohol helps some people to relax when they feel anxious in social activities.

5. The earlier maturity of the reward center partly accounts for adolescents\" risky behavior. 6. Adolescents have to experience a series of anxiety-provoking challenges.

7. Parents should remind their kids that adolescent anxiety is normal and can be got over soon. 8. Researchers found teenagers were prone to get trouble in unlearning the negative feelings linked to the conditioned stimulus.

9. Most teenagers are able to control fear as their prefrontal cortex fully develops in their mid-twenties.

10. The amygdala delivers information about danger to the prefrontal cortex as soon as the **es.

Section B

Passage One

The fridge is considered a necessity. It has been so since the 1960s when packaged food first appeared with the label: \"store in the refrigerator.\"

In my fridgeless fifties childhood, I was fed well and healthily. The milkman came daily, the grocer, the butcher, the baker, and the ice-cream man delivered two or three times a week. The Sunday meat would last until Wednesday and surplus bread and milk became all kinds of cakes. Nothing was wasted, and we were never troubled by rotten food. Thirty years on food deliveries have ceased, flesh vegetables are almost unobtainable in the country.

The invention of the fridge **paratively little to the art of food preservation. A vast way of well-tried techniques already existed—natural cooling, drying, smoking, salting, sugaring, bottling...

What refrigeration did promote was marketing—marketing hardware and electricity, marketing soft drinks, marketing dead bodies of animals around the globe in search of a good price.

Consequently, most of the world\"s fridges are to be found, not in the tropics where they might prove useful, but in the wealthy countries with mild temperatures where they are climatically almost unnecessary. Every winter, millions of fridges hum away continuously, and at vast expense, busily maintaining an artificially-cooled space inside an artificially-heated house—while outside, nature provides the desired temperature free of charge.

The fridge\"s effect upon the environment has been evident, while its contribution to human happiness has been insignificant, If you don\"t believe me, try it yourself, invest in a food cabinet and turn off your fridge next winter. You may miss the hamburgers, but at least you\"ll get rid of that terrible hum.

1. The statement \"In my fridgeless fifties childhood, I was fed well and healthily.\" (Line 1, Para. 2) suggests that ______.

A. the author was well-fed and healthy even without a fridge in his fifties B. the author was not accustomed to use fridges even in his fifties C. there was no fridge in the author\"s home in the 1950s

D. the fridge was in its early stage of development in the 1950s

2. Why does the author say that nothing was wasted before the invention of fridges? A. People would not buy more food than was necessary. B. Food was delivered to people two or three times a week. C. Food was sold fresh and did not get rotten easily. D. People had effective ways to preserve their food.

3. Who benefited the least from fridges according to the author? A. Inventors. B. Consumers. C. Manufacturers. D. Travelling salesmen.

4. Which of the following phrases in the fifth paragraph indicates the fridge\"s negative effect on the environment?

A. \"Hum away continuously\".

B. \"Climatically almost unnecessary\". C. \"Artificially-cooled space\".

D. \"With mild temperatures\".

5. What is the author\"s overall attitude toward fridges? A. Neutral. B. Critical. C. Objective. D. Compromising.

In a country with a shrinking population, the latest trend in Germany\"s higher education is something of a mystery: the number of universities and academic programs is rising. The growth is the sharpest for professional graduate schools, where the number has soared from practically zero in 2003 to 130 now, in fields ranging from law and business to clinical counseling and education. But there is one obvious problem: not enough students are signing up. The German government says that nearly half of professionally oriented programs, aside from law schools, have yet to fill their stated student capacity. And the problem has been especially acute in graduate programs in education.

Interest in many professional schools has been less than overwhelming, said Markus Zimmermann, an executive senior consultant at the Germany Research Institute in Berlin, which is affiliated with Berliner Banking Corp. \"German universities tend torolloutprogramswithout having a good grasp of the needs in the marketplace,\" said Mr. Zimmermann, who watches Germany\"s higher education. \"When they start a program, they assume there will be students.\"

In Germany, the need for graduate programs seems undeniable: lifetime employment is crumbling, employers **mitting less time and money to training young workers, and social problems are becoming **plex, increasing the need for experts. Setting up graduate programs in education was the universities, answer to a growing dissatisfaction with the primary and secondary school system.

With theaccreditation(批准) of the Ministry of Education, 19 universities launched professionally oriented graduate programs in teacher education, seeking approximately 700 students in total. Seven more schools introduced similar programs later. During the first year, 8 of the 19 original institutions fell short of the target enrollment some by far: two schools managed to recruit only half of the target numbers of students. A ministry **pleted shortly afterward said the schools lacked proper marketing methods and had failed to clearly state the practical benefits of receiving graduate diplomas.

Some schools are taking their own measures to increase enrollment. They have gone around visiting undergraduate departments giving explanatory sessions and did what they could to let people know about their programs. The graduate school has also been placing an emphasis on practical training, for example, sending students to teach at local primary and secondary schools. Students teach lessons at local schools, videotape the classes and then bring the tapes back for evaluation with other students. Then they feed the solutions back to the classes. A number of graduate students have had years of teaching experience **ing to the graduate programs, andgenerallyheldpositive views about the in-class training.

6. What is the evident problem of Germany\"s graduate education? A. The deteriorating accreditation environment. B. The soaring number of graduate schools. C. The inadequate graduate enrollment.

D. The narrowing professional oriented fields.

7. According to Markus Zimmermann, why do people lack interest in Germany\"s professional graduate schools?

A. They feel overwhelmed by the pressure of graduate study. B. They are faced with gripping **plicated issues in schools.

C. They see it unnecessary to have graduate study in these programs.

D. They attach more importance to practical ability than academic researches.

8. What led to the establishment of graduate programs in education in German universities? A. The crumbling of lifetime employment. B. The **mitment to employee training. C. The even **plex social problems.

D. The discontent with primary and secondary education.

9. What should graduate schools do to ensure enrollment according to the Ministry of Education? A. Launch more orientation programs. B. Promote the benefits of a master degree. C. Revise the social system for teachers. D. Specify graduate degree requirement.

10. What have schools done to enhance the education of graduates in teaching? A. Identify issues, find solutions and resolve issues in classroom. B. Provide integrated approach to practice and theory. C. Offer students with direct experiences.

D. Arrange and organize students\" knowledge and experiences.

In general, our society is becoming one of giant enterprises directed by a bureaucratic management in which man becomes a small, well-oiled cog (齿轮) in the machinery. The oiling is done with higher wages, well-ventilated factories and piped music, and by psychologists and \"human-relations\" experts; yet all this oiling does not alter the fact that man has become powerless, that he does not wholeheartedly participate in his work and that he is bored with it. In fact, the blue and the white collar workers have become economic puppets (木偶) who dance to the tune of automated machines and bureaucratic management.

The worker and employee are anxious, not only because they might find themselves out of a job; they are anxious also because they are unable to acquire any real satisfaction or interest in life. They live and die without ever having confronted the fundamental realities of human existence as emotionally and intellectually independent and productive human beings.

Those higher up on the social ladder are no less anxious. Their lives are no less empty than those of their subordinates. They are even more insecure in some respects. They are in a **petitive race. To be promoted or to fall behind is not a matter of salary but even more a matter of self-respect. When they apply for their first job, they are tested for intelligence as well as for the right mixture of submissiveness and independence. From that moment on they are tested again and again by the psychologists, for whom testing is a big business, and by their superiors, who judge their behavior, sociability, capacity to get along, etc. This constant need to prove that one is as good as or better than one\"s **petitor creates constant anxiety and stress, the very causes of unhappiness and illness.

Am I suggesting that we should return to the pre-industrial mode of production or to nineteenth-century \"free enterprise\" capitalism (资本主义)? Certainly not. Problems are not solved by returning to a stage which one has already outgrown. I suggest transforming our social system from a bureaucratically managed industrialism in which maximal production and consumption are ends in themselves into a humanist industrialism (工业制度) in which man and

full development of his potentialities-those of love and of reason-are the aims of social arrangements. Production and consumption should serve only as means to this end, and should be prevented from ruling man.

11. Despite **fortable working conditions, employees ______. A. suffer from the feeling of being an automated part of machines B. have to dance with the rhythm of a working machine every day C. cannot put all the energy into work because of family chores

D. always feel tired of the management and bureaucracy of the factory 12. Employees are anxious about themselves because ______. A. they cannot earn as much as they have expected before B. they have to **pete with others for a better position

C. they cannot obtain spiritual satisfaction as a human being D. they are always confronted with fundamental problems of life

13. Those who are superior in position to others may suffer from ______. A. the solitude derived from success B. the fear for the loss of self-respect C. becoming a member of **petitive race

D. the pain of being envied by their subordinates 14. In order to **petitive at work, employees ______.

A. must do endless tests provided by company psychologists B. decide to give up their individual happiness and health C. have to keep an eye constantly on other co-workers

D. have to take the risk of sacrificing both health and happiness 15. In the author\"s opinion, a humanist industrialism ______. A. can prevent employees from becoming economic puppets B. can offer workers a completely successful career C. has the ability to eliminate bureaucracy in any forms D. is a great leap for the freedom of all human beings

Passage Two

For about three centuries we have been doing science, trying science out, using science for the construction of what we call modern civilization. Every dispensable item of contemporary technology, from canal locks to dial telephones to penicillin, was pieced together from the analysis of data provided by one or another series of scientific experiments. Three hundred years seems a long time for testing a new approach to human interaction, long enough to settle back for critical appraisal of the scientific method, maybe even long enough to vote on whether to go on with it or not. There is an argument.

Voices have been raised in protest since the beginning, rising in pitch and violence in the nineteenth century during the early stages of the industrial revolution, summoning urgent crowds into the streets any day on the issue of nuclear energy. The principal discoveries in this century, all in all, are the glimpses of the depth of our ignorance about nature. Things that used to seem clear and rational, matters of absolute certainty—Newtonian mechanics, for example—have slipped

through our fingers, and we are left with a new set of gigantic puzzles, cosmic uncertainties, ambiguities; some of the laws of physics are amended every few years, some are canceled outright, some undergo revised versions of legislative intent as if they were acts of Congress.

Just thirty years ago we call it a biological revolution when the fantastic geometry of the DNA molecule was exposed to public view and the linear language of genetics was decoded. For a while, things seemed simple and clear, the cell was a neat little machine, a mechanical device ready for taking to pieces and reassembling, like a tiny watch. But just in the last few years it has become almost **plex, filled with strange parts whose functions are beyond today\"s imagining. It is not just that there is more to do; there is everything to do. What lies ahead, or what can lie ahead if the efforts in basic research are continued, is much more than the conquest of human disease or the improvement of agricultural technology or the cultivation of nutrients in the sea. As we learn more about fundamental processes of living things in general we will learn more about ourselves.

1. What CAN\"T be inferred from the first paragraph?

A. Scientific experiments in the past three hundred years have produced many valuable items. B. For three hundred years there have been people holding hostile attitude toward science. C. For centuries scientific discoveries have been hailed by the human world unanimously.

D. Three hundred years is not long enough to settle back for critical appraisal of the scientific method.

2. Man\"s attitude toward scientific discoveries has always been ______. A. suspicious B. undoubting C. cynical D. critical

3. Scientists have discovered in the past few years that ______. A. the exposure of DNA to the public is unnecessary B. the tiny cell in DNA is a neat little machine C. man actually knows nothing about DNA D. man has much to learn about DNA

4. What was hailed as a biological revolution thirty years ago? A. Discovery of the structure of DNA．

B. The decoding of the linear language of genetics. C. The mechanical device found in the human cell. D. The **plexity of DNA．

5. The writer\"s main purpose in writing this passage is to say that ______. A. science has greatly improved man\"s life

B. science is far from perfect in exploration of the world C. science has reached its climax in many fields D. science has done too little to human beings

Google recently introduced a new service that adds social-networking features to its popular Gmail system. The service is called Buzz, and within hours of its release, people were howling about privacy issues—because, in its original form, Buzz showed everyone the list of people you e-mail most frequently. Even people who weren\"t cheating on their spouses or secretly applying for new jobs found this a little unnerving.

Google backtracked and changed the software, and apologized for the misstep, claiming that, it just never occurred to us that people might get upset. \"The public reaction was something we did

not anticipate. But we\"ve reacted very quickly to people\"s unhappiness,\" says Bradley Horowitz, vice president for product management at Google.

Same goes for Facebook. In December, Facebook rolled out a new set of privacy settings. A spokesman says the move was intended to \"empower people\" by giving them more \"granular(颗粒)\" control over their personal information. But many viewed the changes as a sneaky attempt to push members to expose more information about themselves—partly because its default settings had lots of data, like your photo, city, gender, and information about your family and relationships, set up to be shared with everyone on the Internet. (Sure, you could change those settings, but it was still creepy.) Facebook\"s spokesman says the open settings reflect \"shifting social norms around privacy.\" Five years after Facebook was founded, he says, \"we\"ve noticed that people are not only sharing more information but also are becoming **fortable about sharing more information with more people.\" Nevertheless, the changes prompted 10 consumer groups to file a complaint with the Federal Trade Commission.

What\"s happening is that our privacy has become a kind of currency. It\"s what we use to pay for online services. Google charges nothing for Gmail; instead, it reads your e-mail and sends you advertisements based on keywords in your private messages.

The genius of Google, Facebook, and others is that they\"ve created services that are so useful or entertaining that people will give up some privacy in order to use them. Now the trick is to get people to give up more—in effect, to keep raising the price of the service.

**panies will never stop trying to chip away at our information. Their entire business model is based on the notion of \"monetizing\" our privacy. To succeed they must slowly change the notion of privacy itself—the \"social norm,\" as Facebook puts it—so that what we\"re giving up doesn\"t seem so valuable. Then they must gain our trust. Thus each new erosion of **es delivered, paradoxically, withrhetoric(华丽的词藻)about how Company X really cares about privacy. I\"m not sure whether Orwell would be appalled or impressed. And who knew Big Brother would be not a big government agency, but a bunch of kids in Silicon Valley? 6. According to the passage, the original form of Buzz______. A. was released to test how people regarded their private rights B. revolutionized the concept of the social networking function C. ruined the reputation of Google\"s well—known Gmail system D. aroused people\"s anger at the time it was added to Gmail system 7. It can be inferred from Bradley Horowitz\"s words that ______. A. Google thought to promote users\" awareness on socializing B. Google made a mistake in judging their users\" needs C. people were in tune with Google\"s developing strategies D. the development of the digital age will change old opinions

8. How does Facebook evaluate people\"s tolerance on private information sharing? A. People can tolerate the private information sharing within the social norms. B. People are still too conservative to share their private information. C. People tend to keep up with the change of social norms on privacy.

D. People have tolerated well when their private information has been shared.

9. According to the passage, the ultimate goal of Google, Facebook and others is to ______. A. upgrade their service to adapt to customers\" needs B. ask customers to pay more for their service

C. provide more entertainments for online users D. persuade users to give up rights on privacy

10. What does the author think of **panies\" strategies on privacy? A. They intrude people\"s privacy under tricky disguise. B. They endeavor to change people\"s ideas on privacy. C. They frighten people to give up some privacy.

D. They take serious responsibility for people\"s privacy.

Europe, where the so-called population explosion got under way in the 18th century, is once again playing a pioneering role in demographic (人口的) development. The continent has the lowest fertility rate and the most elderly population in the world, and this population will soon start to shrink. All this makes it a front runner in a demographic trend that sooner or later will reach most of the world.

Pioneers have to advance through difficult terrain. Economists are already worrying about the problem of how social security systems will cope when the post-war baby boomers start collecting their pensions in 2015. In hyper-ageing countries like Italy and Germany, where 1 in 7 people will be over 80 in 2050, it is unclear how a shrinking group of young people can generate the wealth needed to support the growing group of elderly citizens. Europe\"s **petitiveness could fall behind younger and growing populations in other world regions.

On the face of it, fewer people seem like good news for the environment. The population of Germany, Europe\"s most populous country, will shrink by at least 8 million by 2050 and this trend is set to be replicated in many of its neighbours. Remote rural areas, mainly in central and eastern Europe, might become depopulated over time. This should benefit biodiversity as displaced plant and animal species recolonise their old terrain. Given that the world population is still growing by about 200,000 people a day, and the ecological footprint of the human race already lies beyond the limits of sustainability, fewer European mega-consumers will be a blessing for the health of the planet.

But look a little deeper, and the picture becomes **plicated. Decreasing population does not necessarily promise environmental benefits. The cost per head of population for infrastructure such as sewage systems (污水管道系统) or electricity supply increases when population numbers go down, making clean water and non-polluting energy even more expensive than they are today. So can Europe **e its demographic and ecological challenges at the same time? The solution might be found in a rarely discussed concept: demographic sustainability.

High population growth, such as that now taking place in many African countries, is not sustainable. But very low fertility rates are unsustainable too. It will be hard for countries with persistently low fertility to **petitive, creative and wealthy enough to keep ahead of their country\"s environmental challenges. What is needed is a middle ground.

A demographically sustainable Europe needs to have a stable or slowly shrinking population as the existing infrastructure operates most efficiently when the number of inhabitants remains fairly constant. What would it take to achieve this? At present, the average fertility rate in Europe is 1.5 children per woman, and in countries below this line there is an urgent need for family policies to encourage women to have more children. Countries with fertility rates above 1.8, including France, the UK and Sweden, do not need further pro-birth policies as immigrations will fill the demographic gap.

11. According to the passage, what kind of demographic trend will present in most of the world?

A. Population expansion.

B. The ageing of the population. C. High birth rates. D. High mortality rates.

12. From the economics perspective, what essential effect may the change of the population structure have on Europe\"s countries?

A. Many post-war baby boomers may collect their pensions. B. The living condition of their residents may improve. C. Most of their residents may enjoy the social welfare.

D. **petitiveness may lag behind countries with younger and growing population.

13. According to the passage, the decreasing of population seems to benefit the environment in that

A. it reduces the cost of infrastructure

B. it reduces the emission of carbon dioxide

C. it decreases the consumption of natural recourses

D. it provides a good environment for fostering biodiversity

14. The decreasing of population in fact harms environment in that A. it makes clean water cheap B. it lowers **petition

C. it increases the cost of infrastructure D. it makes no full use of resources

15. How do European countries realise the demographic sustainability? A. By encouraging women to have more children.

B. By keeping the fertility rate above 1.5 and below 1.8. C. By encouraging immigrations to have more children.

D. By taking necessary policies to try to keep a stable population.