单选题California seems to be the home of the homeless since many are often observed {{U}}tramping{{/U}} along railroad tracks and through the downtown areas of the cities.

单选题Internet is a vast network of computers that connects many of the world's businesses, institutions, and individuals. The internet, which means interconnected network of networks, links tens of thousands of smaller computer networks. These networks transmit huge amounts of information in the form of words, images, and sounds. The Internet was information on virtually every topic. Network users can search through sources ranging from vast databases to small electronic "bulletin boards", where users form discussion groups around common interests. Much of the Internet's traffic consists of messages sent from one computer user to another. These messages are called electronic mail or e-mail. Internet users have electronic addresses that allow them to send and receive e-mail. Other uses of the network include obtaining news, joining electronic debates, and playing electronic games. One feature of the Internet, known as the World Wide Web, provides graphics, audio, and video to enhance the information in its documents. These documents cover a vast number of topics. People usually access the Internet with a device called a modem. Modems connect computers to the network through telephone lines. Much of the Internet operates through worldwide telephone networks of fiber optic cables. These cables contain hair thin strands of glass that carry data as pulses of light. They can transmit thousands of times more data than local phone lines, most of which consist of copper wires. The history of the Internet began in the 1960s. At that time, the Advanced Research Projects Agency(ARPA)of the United States Department of Defense developed a network of computers called ARPAnet. Originally, ARPAnet connected only military and government computer systems. Its purpose was to make these systems secure in the event of a disaster or war. Soon after the creation of ARPAnet, universities and other institutions developed their own computer networks. These networks eventually were merged with ARPAnet to form the Internet. By the 1990s, anyone with a computer, modem, and Internet software could link up to the Internet. In the future, the Internet will probably grow more sophisticated as computer technology becomes more powerful. Many experts believe the Internet may become part of a larger network called the information superhighway. This network, still under development, would link computers with telephone companies, cable television stations, and other communication systems. People could bank, shop, watch TV, and perform many other activities through the network.

单选题A man-made chemical that attracts male gypsy moths by duplicating the natural attractant of female gypsy moths has been patented as No. 3,018,219. Dr. Martin Jacobson of Silver Spring, Md., assigned patent rights to the U. S. Government as represented by the Secretary of Agriculture. The chemical can be used to detect gypsy moth infestations, as well as to control the insects. The gypsy moth does serious damage to forest and shade trees in New England and eastern New York State. The caterpillars, or larvae, of gypsy moths eat the leaves of trees, often causing death by a single attack. Losses of hardwood trees have been estimated at tens of millions of dollars from a 20-year study. Gypsy moths were prevented from spreading to other U. S. forest areas by using the natural attractant of the female to detect infestations, then spraying with chemicals such as DDT to kill the insects. Since the lure could previously be obtained only by clipping the last two abdominal segments of the virgin female moth, extracting the segments with benzene and then processing to stabilize the chemical, the procedure was expensive. Another difficulty was that, as the gypsy moth population declined, it became increasingly hard to obtain the females needed for lure production. Dr. Jacobson overcame both these difficulties by discovering a synthetic method for making the female's attractant chemical. The chemical is known as 12-acetoxy-l-hydroxycis-9- octadecene. It is so potent that the fraction of a drop produced by the female is 200,000 times more than the amount needed to catch a mate. The synthetic chemical is also very powerful--it works in amounts about equivalent to one drop in a box car. The flightless female gypsy moth mates only once a year and, as soon as she does, an enzyme switches off production of the sex attractant. The winged male, however, call mate several times and it is because of this that the chemical is being used for pest control. By using a mixture of attractant and DDT in traps lined with a sticky substance, enough males can be caught to reduce the gypsy moth population substantially.

单选题We all have offensive breath at one time or another. In most cases, offensive breath emanates from bacteria in the mouth, although there are other, more surprising causes. Until a few years ago, the most doctors could do was to counsel patients with bad breath about oral cleanliness. Now they are finding new ways to treat the usually curable condition. Bad breath can happen whenever the normal flow of saliva slows. Our mouths are full of bacteria feeding on protein in bits of food and shed tissue. The bacteria emit evil-smelling gases, the worst of which is hydrogen sulfide. Mouth bacteria thrive in airless conditions. Oxygen-rich saliva keeps their numbers down. When we sleep, for example, the saliva stream slows, and sulfur-producing bacteria gain the upper hand, producing classic "morning breath". Alcohol, hunger, too much talking, breathing through the mouth during exercise—anything that dries the mouth produces bad breath. So can stress, though it"s not understood why. Some people"s breath turns sour every time they go on a job interview. Saliva flow gradually slows with age, which explains why the elderly have more bad-breath trouble than younger people do. Babies, however, who make plenty of saliva and whose mouths contain relatively few bacteria have characteristically sweet breath. For most of us, the simple, dry-mouth variety of bad breath is easily cured. Eating or drinking starts saliva and sweeps away many of the bacteria. Breakfast often stops morning breath. Those with chronic dry mouth find that it helps to keep gum, hard candy, or a bottle of water or juice around. Brushing the teeth wipes out dry-mouth bad breath because it clears away many of the offending bacteria. Surprisingly, one thing that rarely works is mouthwash. The liquid can mask bad-breath odor with its own smell, but the effect lasts no more than an hour. Some mouthwashes claim to kill the bacteria responsible for bad breath. The trouble is, they don"t necessarily reach all offending germs. Most bacteria are well protected from mouthwash under thick layers of mucus. If the mouthwash contains alcohol—as most do—it can intensify the problem by drying out the mouth.

单选题The crucial years of the Depression, as they are brought into historical focus, increasingly emerge as the decisive decade for American art, if not for American culture in general. For it was during this decade that many of the conflicts which had blocked the progress of American art in the past came to a head and sometimes boiled over. Janus-faced, the thirties look backward, sometimes as far as the Renaissance; and at the same time forward, as far as the present and beyond. It was the moment when artists, like Thomas Hart Benton, who wished to turn back the clock to regain the virtues of simpler times came into direct conflict with others, like Stuart Davis and Frank Lloyd Wright, who were ready to come to terms with the Machine Age and to deal with its consequences. America in the thirties was changing rapidly. In many areas the past was giving way to the present, although not without a struggle. A Predominantly rural and small town society was being replaced by the giant complexes of the big cities; power was becoming increasingly centralized in the federal government and in large corporations. Many Americans, deeply attached to the old way of life, felt disinherited. At the same time, as immigration decreased and the population became more homogeneous, the need arose in art arid literature to commemorate the ethnic and regional differences that were fast disappearing. Thus, paradoxically, the conviction that art, at least, should serve some purpose or carry some message of moral uplift grew stronger as the Puritan ethos lost its contemporary reality. Often this elevating message was a sermon in favor of just those traditional American virtues, which were now threatened with obsolescence in a changed social and political context. In this new context, the appeal of the paintings by the regionalists and the American Scene painters often lay in their ability to recreate an atmosphere that glorified the traditional American values-self-reliance tempered with good-neighborliness, independence modified by a sense of community, hard work rewarded by a sense of order and purpose. Given the actual temper of the times, these themes were strangely anachronistic, just as the rhetoric supporting political isolationism was equally inappropriate in an international situation soon to involve America in a second world war. Such themes gained popularity because they filled a genome need for a comfortable collective fantasy of a God-fearing, white-picketfence America, which in retrospect took on the nostalgic appeal of a lost Golden Age. In this light, an autonomous art-for-art's sake was viewed as a foreign invader liable to subvert the native American desire for a purposeful art. Abstract art was assigned the role of the villainous alien; realism was to personify the genuine American means of expression. The arguments drew favor in many camps: among the artists, because most were realists; among the politically oriented intellectuals, because abstract art was apolitical; and among museum officials, because they were surfeited with mediocre imitations of European modernism and were convinced that American art must develop its own distinct identity. To help along this road to self-definition, the museums were prepared to set up an artificial double standard, one for American art, and another for European art. In 1934, Ralph Flint wrote in Art News, "We have today in our midst a greater array of what may be called second-, third-, and fourth string artists than any other country. Our big annuals are marvelous outpourings of intelligence and skill; they have all the diversity and animation of a fine-ring circus./

单选题"For all you know, I might have a tremendous burning talent," warns the heroine of Brief Encounter, as the camera pans on to a serenading lady cellist in a teashop trio. "Oh dear, no," comes the reply, "you're too sane and uncomplicated." For a place where talent rarely falls below combustion point, the Royal College of Music is good at not encouraging the cinema stereotype of what it means to be an artist. In fact, the college is too close to the profession it serves to be anything but a breeding ground of serious hard work: there's not time, and very little room for temperament. The proof of industry is quite audible on weekdays during term, when the whole building generates a comfortable din of uncoordinated noise, as pervasive as the English academic smell of polished and cooked cabbage that haunts the corridors. The overall impression is that the college has outgrown its premises as well as its sound-proofing, even though the building in Prince Consort Road has been extended twice. A hundred years ago, when the Royal College came into official existence, it was on a much smaller scale and housed in what is now the Royal College of Organists--a florid piece of 19th-century fantasy beside the Altert Hall. Most students come here straight from school, which is often at a younger age than the current director, Sir David Willcocks, would like, "Singers in particular we encourage to come later, because the voice doesn't really develop until 20 -23. But in practice we accept people before then, rather than see them go elsewhere. If you tell someone to come back in three years time, and he goes off and gets a good job, why should he then risk giving it up to become a student?" Willcocks likes to keep his students for as long as possible, and one of the major policy decisions taken since he came to the college in 1974 has been to increase the length of the basic performers course by a fourth year. "The only ones who could properly go into the profession after three years are wind players, because their standards are astonishingly high these days. Other- wise, my advice is usually to stay here for four years and then perhaps take a specialist course abroad. The most critical recommendation of all—for a student to abandon the idea of a professional performing career—is one that Willcocks rarely has to make. It's in the nature of a conservatoire that progress, or lack of it, is public knowledge; and, given some sensitivity to the competition, most students find their own level without having to be told, "You know when you' ye done well," said one battle-scarred soprano, "because nobody speaks to you." In fact the great majority do carry on with music after they leave the college, but not necessarily in the form they had expected. Conductors may end up repetiteurs in provincial opera houses; solo singers may be swept into the chorus; some are absorbed by arts administration or the BBC, and many become teachers. In all cases, even those who give up music altogether, Willcocks is insistent that they haven't failed: "Music is a discipline in itself, a training of the mind./

单选题The landscape of the Giant's Causeway, lurking below the gaunt sea wall where the land ends, must have struck wonder into the hearts of the ancient Irish, who subsequently felt inspired and created legends about its builder, the giant Finn McCool. The Causeway Coast has an unparalleled display of geological formations representing volcanic activity during the Early Tertiary Period some 50-60 million years ago. Its Tertiary lavas of the Antrim Plateau, covering some 3,800 sq km, represent the largest remaining lava plateau in Europe. The Causeway is a mass of basalt columns packed tightly together. The tops of the columns form stepping stones that lead from the cliff foot and disappear under the sea. Altogether there are 40,000 of these stone columns, mostly hexagonal, but some are quadrangular, pentagonal, heptagonal and octagonal. The tallest ate about 40 feet high, and the solidified lava in the cliffs is 90 feet thick in places. A fine circular walk will take you down to the Giant's Causeway, past amphitheatres of stone columns and formations with fanciful names like the Honeycomb, the Wishing Well, and the Giant's Granny, past a wooden staircase to Benbane Head, and back along the cliff-top. Further down the coast, the stunning Carrick-a-rede rope bridge spans a gaping chasm between the coast and a small island used by fishermen. The eighty-foot drop can be crossed via the swinging bridge- and is not for the faint-hearted! The Giant's Causeway and Causeway Coast site was inscribed as a World Heritage Site by UNESCO in 1986. The site is of outstanding universal value and meets the criteria set in the World Heritage Convention. Namely, it is an outstanding example representing major stages of the earth's history including the record of life: significant on-going geological processes in landform developments, and significant geomorphic and physiographic features; moreover, it also contains superlative natural phenomena and areas of exceptional natural beauty and aesthetic importance. Moyle District Council's Causeway Visitor Centre is open daily all year round and located on the cliff top 1 km from the site. The Centre is the ideal starting point for walks along the coastal and cliff-top paths, providing all excellent range of visitor services. A 12-minute audio-visual presentation, with commentary available in 5 European languages, enables visitors to further explore the origins of the Giant s Causeway through local folklore~ and scientific theory, and highlights the many other attractions of the Causeway Coast and Glens of Antrim area.

单选题Australia began to assume its modern configuration by the Eocene Epoch, some 50 million years ago, when Antarctica broke away and drifted southward.

单选题What do the words "remain stationary" mean in sentence 1, paragraph 4 of the passage?

单选题One weakness of this study may be ______.

单选题In mountainous regions, much of the snow that falls is Ucompacted/U into ice.

单选题Two of the girls have to share one bed, but the other three have______ones.

单选题It is said that in England death is pressing, in Canada inevitable and in California optional. Small wonder. Americans' life expectancy has nearly doubled over the past century. Failing hips can be replaced, cataracts removed in a 30-minutes surgical procedure. Such advances offer the aging population a quality of life that was unimaginable when I entered medicine 50 years ago. But not even a great health-care system can cure death, and our failure to confront that reality now threatens this greatness of ours. Death is normal; we are genetically programmed to disintegrate and perish, even under ideal conditions. We all understand that at some level, yet as medical consumers we treat death as a problem to be solved. Shielded by third-party payers from the cost of our care, we demand everything that can possibly be done for us, even if it's useless. The most obvious example is late-stage cancer care. Physicians — frustrated by their inability to cure the disease and fearing loss of hope in the patient — too often offer aggressive treatment far beyond what is scientifically justified. In 1950, the U.S. spent $12.7 billion on health care. In 2002, the cost will be $ 1,540 billion. Anyone can see this trend is unsustainable. Yet few seem willing to try to reverse it. Some scholars conclude that a government with finite resources should simply stop paying for medical care that sustains life beyond a certain age — say 83 or so. Former Colorado governor Richard Lamm has been quoted as saying that the old and infirm "have a duty to die and get out of the way", so that younger, healthier people can realize their potential. I would not go that far. Energetic people now routinely work through their 60s and beyond, and remain dazzlingly productive. At 78, Viacom chairman Sumner Redstone jokingly claims to be 53. Supreme Court Justice Sandra Day O'Connor is in her 70s, and former surgeon general C. Everett Koop chairs an Internet start-up in his 80s. These leaders are living proof that prevention works and that we can manage the health problems that come naturally with age. As a mere 68-year-old, I wish to age as productively as they have. Yet there are limits to what a society can spend in this pursuit. As a physician, I know the most costly and dramatic measures may be ineffective and painful. I also know that people in Japan and Sweden, countries that spend far less on medical care, have achieved longer, healthier lives than we have. As a nation, we may be overfunding the quest for unlikely cures while underfunding research on humbler therapies that could improve people's lives.

单选题One of the most important periods in Greed history was the Hellenistic Age which began after the death of Alexander the Great in 323 B.C. , and lasted almost 200 years. It was during this time in history that Greek ideas and Greek culture spread to Egypt and throughout the Near East. A Greek state even existed as far west as India. During the Hellenistic Age, there were great advances in such areas as philosophy, science, religion, art and social justice. Important discoveries were made in the sciences. Eratosthenes, for instance, made an accurate calculation of the diameter of the earth, while Aristarchus declared that the earth was round. Social reformers attempted to abolish debt and institute a program of land redistribution among the poor but met with little success. Women achieved a better social standing and among the middle class education became widespread. Peace of mind was the great concern of the philosophers of the Hellenistic Age. The Stoics insisted that happiness could be achieved when man learned to accept the events which were beyond his control and, at the same time, did his duty. The Epicureans espoused the idea that moderation in pleasure and the avoidance of pain produced the desired result. The Cynics turned away from all desires and pleasures, and advocated a pursuit of virtue. In religion, many Greeks turned to the worship of such Egyptian gods as Serapis and Isis. During the Hellenistic Age, the area of Greek influence included such political powers as the Ptolemies of Egypt, the Seleucids of Syria, the Antigonids of Macedon and the Attalids of Pergamum, and it was their fighting against each other and among themselves that paved the way for the aggressive Romans to conquer Greece and most of the Hellenistic world in the 100's B. C. The Romans brought the Hellenistic Age to a close when they conquered the last major power, Egypt, in 30 B. C.

单选题Another common ______ about older people is that they are too old to learn new skills.

单选题To save money for my education, Mother often took on more work than ______ for her.

单选题Your left ______ hemisphere controls the right-hand side of your body.

单选题Mary Robinson has been formally ______ as Ireland's first woman president. A. sworn in B. told off C. spelt out D. picked up