单选题Mark Twain once observed that giving up smoking is easy. He knew, because he'd done it hundreds of times himself. Giving up for ever is a trifle more difficult, apparently, and it is well known that it is much more difficult for some people than for others. Why is this so? Few doctors believe any longer that it is simply a question of will power. And for those people that continue to view addicts as merely "weak", recent genetic research may force a rethink. A study conducted by Jacqueline Vink, of the Free University of Amsterdam, used a database called the Netherlands Twin Register to analyse the smoking habits of twins. Her results suggest that an individual's degree of nicotine dependence, and even the number of cigarettes he smokes per day, are strongly genetically influenced. The Netherlands Twin Register is a voluntary database that is prized by geneticists because they allow the comparison of identical twins (who share all their genes) with fraternal twins (who share half). In this case, however, Dr. Vink did not make use of that fact. For her, the database was merely a convenient repository of information. Instead of comparing identical and fraternal twins, she concentrated on the adult fraternal twins, most of whom had completed questionnaires about their habits, including smoking, and 536 of whom had given DNA samples to the register. The human genome is huge. It consists of billions of DNA "letters", some of which can be strung together to make sense (the genes), but many of which have either no function, or an unknown function. To follow what is going on, geneticists rely on markers they have identified within the genome. These are places where the genetic letters may vary between individuals. If a particular variant is routinely associated with a particular physical feature or a behaviour pattern, it suggests that a particular version of a nearby gene is influencing that feature or behaviour. Dr. Vink hopes that finding genes responsible for nicotine dependence will make it possible to identify the causes of such dependence. That will help to classify smokers better (some are social smokers while others are physically addicted) and thus enable "quitting" programmes to be customised. Results such as Dr. Vink's must be interpreted with care. Association studies, as such projects are known, have a disturbing habit of disappearing, as it were, in a puff of smoke when someone tries to replicate them. But if Dr. Vink really has exposed a genetic link with addiction, then Mark Twain's problem may eventually become a thing of the past.

单选题4 The evolution of sex ratios has produced, in most plants and animals with separate sexes, approximately equal numbers of males and females. Why should this be so? Two main kinds of answers have been offered. One is couched in terms of advantage to popula tion. It is argued that the sex ratio will evolve so as to maximize the number of meetings be tween individuals of the opposite sex. This is essentially a "group selection" argu- ment. The other, and in my view correct, type of answer was first put forward by Fisher in 1930. This "genetic" argument starts from the assumption that genes can influence the relative numbers of male and female offspring produced by an individual carrying the genes. That sex ratio will be favored which maximizes the number of descendants an indi vidual will have and hence the number of gene copies transmitted. Suppose that the popula tion consisted mostly of females, then an individual who produced sons only would have more grandchildren. In contrast, if the population consisted mostly of males, it would pay to have daughters. If, however, the population consisted of equal numbers of males and females, sons and daughters would be equally valuable. Thus a one-to-one sex ratio is the only stable ratio; it is an "evolutionarily stable strategy. " Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essen tial feature of a game that the best strategy to adopt depends on what others are doing. Since Fisher's time, it has been realized that genes can sometimes influence the chro mosome or gamete in which they find themselves so that the gamete will be more likely to participate in fertilization. If such a gene occurs on a sex-determining (X or Y) chromo some, then highly aberrant sex ratios can occur. But more immediately relevant to game theory are the sex ratios in certain parasitic wasp species that have a large excess of fe males. In these species, fertilized eggs develop into females and unfertilized eggs into males. A female stores sperm and can determine the sex of each egg she lays by fertilizing it or leaving it unfertilized. By Fisher's argument, it should still pay a female to produce equal numbers of sons and daughters. Hamilton, noting that the eggs develop within their host--the larva of another insect--and that the newly emerged adult wasps mate immedi ately and disperse, offered a remarkably cogent analysis. Since only one female usually eggs in a given larva, it would pay her to produce one male only, because this one could fertilize all his sisters on emergence. Like Fisher, Hamilton looked for an evolutionarily stable strategy, but he went a step further in recognizing that he was looking for a strate gy.

单选题A group of top Chinese scientists will ______.

单选题{{B}}Text 3{{/B}} Culture is the total sum of all the traditions, customs, belief and ways of life of a given group of human beings. In this sense, every group has a culture, however savage, undeveloped, or uncivilized it may seem to us. To the professional anthropologist, there is no intrinsic superiority of one culture ever another, just as to the professional linguist there is no intrinsic hierarchy among languages. People once thought of the languages of backward groups as savage, undeveloped forms of speech, consisting largely of grants and groans. While it is possible that language in ganeral began as a series of grunts and groans, it is a fact established by the study of "backward" languages that no spoken tongue answers that description today. Most languages of uncivilized groups are, by our most severe standards, extremely complex, delicate, and ingenious pieces of machinery for the transfer of ideas. They fall behind the Western languages not in their sound patterns or grammatical structures, which usually are fully adequate for all language needs, but only in their vocabularies, which reflect the objects and activities known to their speakers. Even in this department, however, two things are to be noted: 1. All languages seem to possess the machinery for vocabulary expansion, either by putting together words already in existence or by borrowing them from other languages and adapting them to their own system. 2. The objects and activities requiring names and distinctions in "backward" languages, while different from oars, are often surprisingly numerous and complicated. A western language distinguishes merely between two degrees of remoteness ("this" and "that"); some languages of the American Indians distinguish between what is close to the speaker, or the person addressed, or remote from both, or out of sight, or in the past, or in the future. This study of language, in turn, casts a new light upon the claim of the anthropologists that all cultures are to be viewed independently, and without ideas of rank or hierarchy.

单选题This question is ______ easy. A) extremely B) completely C) totally D) highly

单选题The man lost his______just because his secretary was ten minutes late.

单选题{{B}}Text 2{{/B}} For more than two decades, U.S. courts have been limiting affirmative-action programs in universities and other areas. The legal rationale is that racial preferences are unconstitutional, even those intended to compensate for racism or intolerance. For many colleges, this means students can be admitted only on merit, not on their race or ethnicity. It has been a divisive issue across the U. S., as educators blame the prolonged reaction to affirmative-action for declines in minority admissions. Meanwhile, activists continue to battle race preferences in courts from Michigan to North Carolina. Now chief executives of about two dozen companies have decided to plunge headfirst into this politically unsettled debate. They, together with 36 universities and 7 non-profitable organizations, formed a forum that set forth an action plan essentially designed to help colleges circumvent court-imposed restrictions on affirmative action. The CEOs' motive: "Our audience is growing more diverse, so the communities we serve benefit if our employees are racially and ethnically diverse" as well, says one CEO of a company that owns nine television stations. Among the steps the form is pushing: finding creative yet legal ways to boost minority enrollment through new admissions policies; promoting admissions decisions that look at more than test scores; and encouraging universities to step up their minority outreach and financial aid. And to counter accusations by critics to challenge these tactics in court, the group says it will give legal assistance to colleges sued for trying them. "Diversity diminished by the court must be made up for in other legitimate, legal ways," says a forum member. One of the more controversial methods advocated is the so-called 10% rule. The idea is for public universities--which educate three-quarters of all U. S. undergraduates--to admit students Who are in the top 10% of their high school graduating class. Doing so allows colleges to take minorities who excel in average urban schools, even if they wouldn't have made the cut under the current statewide ranking many universities use.

单选题Music and paintings can communicate one's______feelings and emotions when words fail to express them.

单选题Allen will soon find out that real life is seldom as simple as it is ______ in commercials.(2006年中南大学考博试题)

单选题In terms of the meaning expressed by words, they can be classified into ______.

单选题According to the passage, which of the following statements is true? A. Wales is the richest of the three. B. Scotland is the largest of the three. C. Sometimes English is used instead of Britain. D. Britain is the only name of the largest island of British Isles.

单选题Wolfgang was quiet when his sister practised the piano because ______.

单选题For eighty years Thomas"s family had grown corn on its hundred-acre plot. In his grandfather"s day, even in his father"s, wheat and timothy were also sown to help feed cattle and pigs. While there had been no animals on the land in Thomas"s time, Thomas"s father spoke at length about those days, when he himself had been a child. Back then, Thomas"s father had dedicated every one of his free hours to taking care of the farm; grinding chop, cleaning up after the animals, mending fences, and performing innumerable other taxing chores. Later, it was just corn, sold to some big company out East that his father said paid them a little less every year. It wasn"t about the money though; his father would have made do just enough to keep things going. His concern was family and tradition, the agricultural way of life. During harvest, Thomas would ride on the enormous thresher with his father. In the cabin, above the green sea parting before them, he would listen as his father explained the significance of a life dedicated to agriculture. As Thomas nibbbled on a lunch packed by his mother, his father expounded upon his philosophy that a man must not be separated from the land that provides for him, that the land was very important. He would say, time and again, "A man isn"t a man without land to call his own. " He was not an uneducated man, Thomas"s father. He had completed high school and probably could have gone to college if he wanted, but he was a man of the earth, and his spirit was tied to the soil. Agriculture was not his profession; it was his passion, one that he tried to seed in the hearts of his three boys. Thomas"s two older brothers had little time for farmwork, however. What chores they were not forced to do went undone or were done by Thomas; their energies were focused on cars, dating, and dance halls. Even at a young age, Thomas was able to see in his father"s eyes the older man"s secret despair. The land that had been in his family for three generations was not valued by the fourth. Not even little Tommy, who always rode in the cabin with him and helped out as much as he was able, would stay and tend the fields. The world had grown too large, and there were too many distractions to lure young men from their homes. Boys these days did not realize they had a home until it was too late. Sitting on the hood of his jeep, Thomas gazed out over dozens of acres of orange survey stakes that covered what was once his family"s farm. The house, barn, and silos were all gone, replaced by construction trailers and heavy equipment. The town that lay just five miles up the road had grown into a city, consuming land like a hungry beast. Thomas"s father had been the last farmer left in the county, holding out long after the farm became unprofitable. He farmed after his sons left and his wife died; he farmed until his last breath, on principle. Now a highway and several shopping malls were going to take his place, Thomas thought. His brothers both said it was inevitable, that progress cannot be halted. They argued that if the family did not sell the land, the city would claim eminent domain and take it from them for a fraction of what they could get by selling it. Thomas did not feel he had any right to disagree. After all, he had chosen to leave the farm as well, to pursue his education. Though he didn"t stand in their way, and though his profit from the lucrative sale was equal to his brothers", Thomas was sure he felt something that they could not. The money didn"t matter much to him; he had enough to get by. It was something about the land. Now that he had finally found his way back to it, he was losing it. He was losing his home.

单选题Television is one of today's most powerful and widespread means of mass communication. It directly influences our lives on both a short and long-term basis; it brings worldwide situations into our homes; it affords extensive opportunities for acquiring higher education; and it performs these tasks in a convenient yet effective manner. We are all aware of the popularly accepted applications of television, particularly those relative to entertainment and news broadcasting. Television, however, has also been a vital link in unmanned deep space exploration (such as the Voyager Ⅰ and Ⅱ missions), in providing visions from hazardous areas (such as proximity to radioactive materials or environments) in underwater research, in viewing storms moving across a metropolitan area (the camera being placed in a weather-protective enclosure near the top of a tower) , etc. The earth's weather satellites also use television cameras for viewing cloud cover and movements from 20, 000 miles in space. Infrared filters are used for night views, and several systems include a spinning mirror arrangement to permit wide-area views from the camera. Realizing the unlimited applications for today's television, one may thus logically ponder the true benefits of confining most of our video activities to the mass-entertainment field. Conventional television broadcasting within the United States centres around free enterprise and public ownership. This requires funding by commercial sponsors, and thus functions in a revenue-producing business manner. Television in USSR-subjected areas, conversely, is a government-owned and maintained arrangement. While such arrangements eliminate the need for commercial sponsorship, it also has the possibility of limiting the type of programs available to viewers (a number of purely entertainment programs similar to the classic "Bewitched", however, have been seen on these government-controlled networks. All isn't as gray and dismal as the uninformed might unnecessarily visualize). A highly modified form of television called Slow-Scan TV is presently being used by many Amateur Radio operators to provide direct visual communications with almost any area of the world. This unique visual mode recently allowed people on the tiny South Pacific country of Pitcairn Island to view, for the first time in their lives, distant areas and people of the world. The chief radio Amateur and communications officer of Pitcairn, incidentally, is the legendary Tom Christian-great, great grandson of Tom Christian of "Mutiny on the Bounty" fame. Radio Amateurs in many lands worked together for several months establishing visual capabilities. The results have proven spectacular, yet the visual capabilities have only been used for health education, or welfare purposes. Commercial TV is still unknown to natives of that tiny country. Numerous other forms of television and visual communication have also been used on a semi-restricted basis. This indicates the many untapped areas of video and television which may soon be exploited on a more widespread basis. The old clich of a picture being worth a thousand words truly has merit.

单选题Myfriendsurgedmenot __________ theopportunityforitmightnevercomeagain

单选题The article is most likely a part of______

单选题The supply of electric power to the city and its neighboring districts has had to be______.

单选题As we have seen, the focus of medical care in our society has been shifting from curing disease to preventing disease—especially in terms of changing our many unhealthy behaviors, such as poor eating habits, smoking, and failure to exercise. The line of thought involved in this shift can be pursued further. Imagine a person who is about the fight weight, but does not ear very nutritious goods, who feels OK but exercises only occasionally. This person is not ill. She/He may not even be at risk for any particular disease. But we can imagine that this person could be a lot healthier. The field of medicine has not traditionally distinguished between someone who is merely "not ill" and someone who is in excellent health and pays attention to the body"s special needs. Both types have simply been called "well". In recent years, however, some health specialists have begun to apply the terms "well" and "wellness" only to those who are actively striving to maintain and improve their health. People who are well are concerned with nutrition and exercise, and they make a point of monitoring their body"s condition. Most important, perhaps, people who are well take active responsibility for all matters related to their health. Even people who have a physical disease or handicap may be "well" in this new sense, if they make an effort to maintain the best possible health they can in the face of their physical limitations. "Wellness" may perhaps best be viewed not as a state that people can achieve, but as an ideal that people can strive for. People who are well are likely to be better able to resist disease and to fight disease when it strikes. And by focusing attention on healthy ways of living, the concept of wellness can have a beneficial impact on the ways in which people face the challenges of daily life.