单选题For a solid or liquid fuel to ______, some of the fuel must first be heated to the temperature at which it turns to a gas.

单选题Charles Darwin's "On the Origin of Species" is credited with sparking evolution's revolution in scientific thought, but many observers had pondered evolution before him. It was understanding the idea's significance and selling it to the public that made Darwin great, according to the Arnold Arboretum's new director. William Friedman, the Arnold Professor of Organism and Evolutionary Biology who took over as arboretum director Jan. 1, has studied Darwin's writings as well as those of his predecessors and contemporaries. While Darwin is widely credited as the father of evolution, Friedman said the "historical sketch" that Darwin attached to later printings of his masterpiece was intended to mollify those who demanded credit for their own earlier ideas. The historical sketch grew with each subsequent printing, Friedman told an audience Monday (Jan. 10), until, by the 6th edition, 34 authors were mentioned in it. Scholars now believe that somewhere between 50 and 60 authors had beaten Darwin in their writings about evolution. Included was Darwin's grandfather, Erasmus Darwin, a physician who irritated clergymen with his insistence that life arose from lower forms, specifically mollusks. Friedman's talk, "A Darwinian Look at Darwin's Evolutionist Ancestors," took place at the arboretum's Hunnewell Building and was the first in a new Director's Lecture Series. Though others had clearly pondered evolution before Darwin, he wasn't without originality. Friedman said that Darwin's thinking on natural selection as the mechanism of evolution was shared by few, most prominently Alfred Wallace, whose writing on the subject after years in the field spurred Darwin's writing of "On the Origin of Species. " Although the book runs more than 400 pages, Friedman said it was never the book on evolution and natural selection that Darwin intended. In 1856, three years before the book was published, he began work on a detailed tome on natural selection that wouldn't see publication until 1975. The seminal event in creating "On the Origin of Species" occurred in 1858, when Wallace wrote Darwin detailing Wallace's ideas of evolution by natural selection. The arrival of Wallace's ideas galvanized Darwin into writing "On the Origin of Species" as an "abstract" of the ideas he was painstakingly laying out in the larger work. This was a lucky break for Darwin, because it forced him to write his ideas in plain language, which led to a book that was not only revolutionary, despite those who'd tread similar ground before, but that was also very readable. Though others thought about evolution before Darwin, scientific discovery requires more than just an idea. In addition to the concept, discovery requires the understanding of the significance of the idea, something some of the earlier authors clearly did not have— such as the arborist who buried his thoughts on natural selection in the appendix of a book on naval timber. Lastly, scientific discovery demands the ability to convince others of the correctness of an idea. Darwin, through "On the Origin of Species," was the only thinker of the time who had all three of those traits, Friedman said. "Darwin had the ability to convince others of the correctness of the idea," Friedman said, adding that even Wallace, whose claim to new thinking on evolution and natural selection was stronger than all the others, paid homage to Darwin by titling his 1889 book on the subject, "Darwinism. /

单选题The rough guide to marketing success used to be that you got what you paid for. No longer. While traditional " paid" media — such as television commercials and print advertisements — still play a major role, companies today can exploit many alternative forms of media. Consumers passionate about a product may create " earned" media by willingly promoting it to friends, and a company may leverage "owned" media by sending e-mail alerts about products and sales to customers registered with its Web site. In fact, the way consumers now approach the process of making purchase decisions means that marketing's impact stems from a broad range of factors beyond conventional paid media. Paid and owned media are controlled by marketers promoting their own products. For earned media , such marketers act as the initiator for users' responses. But in some cases, one marketer's owned media become another marketer's paid media — for instance, when an e-commerce retailer sells ad space on its Web site. We define such sold media as owned media whose traffic is so strong that other organizations place their content or e-commerce engines within that environment. This trend , which we believe is still in its infancy, effectively began with retailers and travel providers such as airlines and hotels and will no doubt go further. Johnson & Johnson, for example, has created BabyCenter, a stand-alone media property that promotes complementary and even competitive products. Besides generating income, the presence of other marketers makes the site seem objective, gives companies opportunities to learn valuable information about the appeal of other companies' marketing, and may help expand user traffic for all companies concerned. The same dramatic technological changes that have provided marketers with more(and more diverse)communications choices have also increased the risk that passionate consumers will voice their opinions in quicker, more visible, and much more damaging ways. Such hijacked media are the opposite of earned media: an asset or campaign becomes hostage to consumers, other stakeholders, or activists who make negative allegations about a brand or product. Members of social networks, for instance, are learning that they can hijack media to apply pressure on the businesses that originally created them. If that happens, passionate consumers would try to persuade others to boycott products, putting the reputation of the target company at risk. In such a case, the company's response may not be sufficiently quick or thoughtful, and the learning curve has been steep. Toyota Motor, for example, alleviated some of the damage from its recall crisis earlier this year with a relatively quick and well-orchestrated social-media response campaign, which included efforts to engage with consumers directly on sites such as Twitter and the social-news site Digg.

单选题Each person's genetic code is unique except ______ identical twins. A. in case of B. in the case of C. the point in case D. a case of

单选题Walls and wail building have played a very important role in Chinese culture. These people, from the dim mists of prehistory have been wall-conscious; from the Neolithic period—when ramparts of pounded earth were used-to the Communist Revolution, walls were an essential part of any village. Not only towns and villages, the houses and the temples within them were somehow walled, and the houses also had no windows overlooking the street, thus giving the feeling of wandering around a huge maze. The name for "city" in Chinese means wall, and over these walled cities, villages, houses and temples presides the god of walls and mounts, whose duties were, and still are, to protect and be responsible for the welfare of the inhabitants. Thus a great and extremely laborious task such as constructing a wall, which was supposed to run through the country, must not have seemed such an absurdity. However, it is indeed a commom mistake to perceive the great wall as a single architectural structure, and it would also be erroneous to assume that it was built during a single dynasty. For the building of the wall spanned the various dynasties, and each of these dynasties somehow contributed to the reburbishing and the construction of a wall, whose foundations had been laid many centuries ago. It was during the fourth and third century B.C. that each warring state started building walls to protect their kingdoms, both against one another and against the northern nomads. Especially three of these states: the Qin, the Zhao and the Yan, corresponding respectively to the modern provinces of Shanxi, Shaanxi and Hebei, over and above building walls that surrounded their kindoms, also laid the foundations on which Qin Shih Huang Di would build his first continuous Great Wall. The role that the Great Wall played in the growth of Chinese economy was an important one. Throughout the centuries many settlements were established along the new border. The garrison troops were instructed to reclaim wasteland and to plant crops on it, roads and canals were built, to mention just a few of the works carried out. All these undertakings greatly helped to increase the country"s trade and cultural exchanges with many remote areas and also with the southern, central and western parts of Asia—the formation of the Silk Route. Builders, garrisons, artisans, farmers and peasants left behind a trail of objects, including inscribed tablets, household articles, and written work, which have become extremely valuable archaeological evidence to the study of defense institutions of the Great Wall and the everyday life of these people who lived and died along the wall.

单选题There can be no question about the dangers of heroin use. What may start out innocently enough as a desire to experience a new kind of high may progress with extreme rapidity to an almost continuous type of nightmare existence. The heroin user may begin by snorting or inhaling the drug, progress to "skin popping" (injecting it beneath the skin), and end up "mainlining" it (injecting it directly into the bloodstream). If a hypodermic syringe is not available, the user may sever an artery and pour the heroin in with a spoon. Once users are "hooked", their entire lives become centered upon this white powder. They will do anything--lie, steal, cheat, even kill--to get that next fix. After a while, riley do not even experience a high; they simply need the drug to avoid the terrors of withdrawal. The habit demands more and more, and still more, of the drug. Even a highly paid corporation executive would find it difficult to support such a habit. Usually, the only way the addict can get enough money is through crime or prostitution. Thus, crime associated with heroin addiction is not a direct effect of the drug, but stems from the need to support the habit. In fact, heroin is an extremely effective depressant, which markedly reduces such motivational states as hunger and sex. How is it that this innocent-looking white powder can come to dominate the life of the abuser so completely? Within the first minute of heroin injection, there is a sudden, climactic rush of feeling. This extremely pleasurable experience is followed by a "high" which is characterized by lethargy, emotional detachment, a sense of well-being, and deep feelings of contentment. To illustrate, a heroin abuser may spend hours before a TV set, watching the dancing images on the screen without becoming emotionally involved in the program content. But then comes the crushing aftermath. As the high begins to subside, so also does the sense of well-being. The euphoria of a moment ago is replaced by gnawing feelings of apprehension and anxiety. The bizarre cycle culminates in an overwhelming sense of panic as the addict begins a frantic search for tile next fix. The victims of heroin addiction are legion--the addicts themselves, their families, and those they have robbed or otherwise brutalized in their quest for the "big H". In recent years another innocent victim of heroin addiction has come to light, the newborn infant of an addicted mother. Studies of infants born to heroin-addicted mothers have found that more than two-thirds start out life as addicts. Within 96 hours of birth, most will show signs of withdrawal, including extreme irritability, tremors, and vomiting. The incidence of withdrawal symptoms in the newborn depends on how long the mother has been addicted, on the amount of heroin she has taken, and on how close to delivery she was when she took her last dose. Traces of drugs taken as little as ten minutes prior to delivery have been found in newborns.

单选题This computer is up-to-date ______ a few shortcomings here and there.

单选题John was surprised to ______ Matthew at the football game.

单选题The position of Burleigh School in the English educational system would be very difficult to explain to a foreigner (who has, God knows, enough to contend with in comprehending the other parts of the system). Nor would it be possible to refer him to any works of literature (before the present one) from which he could gain enlightenment. The prep schools have had their Orwell, the public schools their Connolly and Benedictus, the convent schools their Antonia White, the private boarding schools their Waugh and Nicolas Blake. No one has thought it worth their while to eulogize or anathematize schools like Burleigh. Indeed, schools like Burleigh do not seem the sort of places from which writers emerge. And yet, any medium-sized town in the southern half of England has its Burleigh School: a private day school to which, for a not too exorbitant fee, parents can send their children and boast that they are privately educated. Not well educated, but privately. Burleigh itself had been founded--no, started--between the wars, had survived the Depression (as the South of England middle classes in general had so signally managed to coast blithely through the Depression) and had offered over the years an alternative to the Grammar, Secondary Modern and Technical Schools of the town of Cullbridge. Which meant, in effect, that though some parents chose to send their children there rather than to the Grammar School, many more sent them there because they failed their eleven-plus, that Beecher's Brook of English childhood. With the coming of comprehensive education three years before, even the faint whiff of privilege attached to the Grammar School had evaporated, a fact on which Burleigh had been able to capitalize, in a mild way. Foreigners are always apt to find charming the examples they come across of quaint anachronisms, of dated anomalies, in English life. One such charming and dated anomaly is that a school like Burleigh can be bought. A man--any man--can buy such a place, set himself up as headmaster, and run it as he likes. Indeed, that is precisely what Edward Crumwallis had done. He had bought it from its previous aging owner/headmaster in 1969, and had been there ever since. This must not be taken to imply that Edward Crumwallis was unfit for his position. He was in fact a BA (3rd class, Geography), from the University of Hull (graduated 1948). Still, scholarship was not exactly his thing. He might take the odd class in Geography in a pinch, but he had never given the subject any particular prominence in the school, and most boys gave it up after two years. Nor was Crumwallis anxious to take over periods in other subjects when there was need--as in cases of sickness or (frequently) death. Since his graduation he had not cultivated Learning. He had cultivated Manner. He had bought Burleigh (which he invariably called The Burleigh School, in capitals) precisely so that his manner might be given free reign and ample pasturage. A very good manner it was too, with parents-- decidedly impressive, ft certainly impressed those of limited intelligence, among whom may be numbered-Crumwallis himself. He really believed in it: he not only thought that others should remain silent during his threadbare pontifications, but he actually believed they would benefit from them. Such a conspicuous lack of self-knowledge had its dangers. Not that the Manner--which he intended should be so admired later in the week On Parents' Evening--was particularly in evidence on the Monday, as he sat at his study desk and went over the plans for that event with his wife. The side of Edward Crumwallis that was most evident during such t·te-·-·tes was the petty-minded, niggling side that his psychological profile seldom turned in the parents' direction. "The question is, shall we splurge on the coffee and scrimp on the tea, or vice versa," he said.

单选题The doctor assured her that the pain would ______.

单选题The prices of all the shares fell sharply just after a few ______ when the news came that the war had broken out.

单选题It took a lot of imagination to come up with such an______plan.(2005年春季电子科技大学考博试题)

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单选题Paper clips, drawing pins and safety-pins were______all over the floor.

单选题On any corner, sane men, fanatics and demagogues could secure audiences to listen to their oratory, in which they adjured their hearers to rise in their might and drive the invader from their sacred soil.

单选题The more intrusive advertisements become, the more they irritate web users.(清华大学2006年试题)

单选题Likenesses of Buddha are these days SO commonplace—the casual adornment of fashionable spas, fusion restaurants and Parisian nightclubs—that it is strange to think that artists once hesitated, out of reverence, to portray the Buddha in corporeal form. In 2nd century India, judging by a 2nd century sandstone carving excavated from Mathura, it was sufficient to simply depict an empty throne—the implication that the Buddha was a spiritual king being very clearly understood by anyone who saw it. But as the stunning new gallery of Buddhist sculpture at London"s Victoria and Albert Museum makes Plain, somewhere along the line the reticence (沉默) about rendering the Buddha"s likeness gave way, and the world embarked on two millenniums of rich iconography and statuary. The gallery"s 47 masterworks, chosen from the museum"s renowned Asian collections, trace the Buddha"s portrayal from the 2nd to the 19th centuries, in places as diverse as India, Java and Japan. Inspiration came from unexpected sources. Some sculptors in Sri Lanka and China simply shaped the Buddha in their own likenesses. A 4th century stucco bust unearthed in Afghanistan features the full lips associated with Indian Gupta art, but also fulsome curls that reflect the Greco-Roman artists brought to the region by Alexander the Great. Other enlightened souls are shown beside the Buddha. Among the gallery"s most glorious artifacts are depictions of bodhisattvas—those who deliberately postpone their passage to nirvana (涅槃), Buddhists believe, in order to help others along the eightfold path. In the 14th century, metalworkers from Nepal"s Kathmandu Valley crafted the Bodhisattva Avalokiteshvara, a manifestation of the Buddhist lord of compassion, in gilded copper and precious-stone inlay. An androgYnous-looking deity with wide hips and sensuous form (in Chinese tradition, Avalokiteshvara or Guan Yin is female, in others male), Avalokiteshvara"s serene face projects the harmony to which all Buddhists aspire. John Clarke, the gallery"s principal curator, says that Avalokiteshvara is sometimes depicted holding a blooming lotus—a symbol of spiritual purity. "It comes up from the mud, flowers, and remains untouched by the dirt that surrounded it," he says. You could say the same thing for the wonderful richness of Buddhist art.

单选题The economy in this region has been stagnant for a long time and no signs of recovery have ______ till now.

单选题Some crystals emit visible light when ______ by ionizing particles.