单选题A crowd gathered to see what had happened.

单选题It is {{U}}absurd{{/U}} to go out in such terrible weather.

单选题The used car {{U}}lot{{/U}} open until 9 o'clock.

单选题The Ice Age Twenty thousand years ago, the earth was held in control by relentlessly (不宽容地) probing fingers of ice that drew power from frigid strongholds in the north and crept southwestward to bury forests, fields, and mountains. Landscapes that were violated by the slowly moving glaciers(冰川)would carry the scars of this advance far into the future. Temperatures dropped deeply, and land surfaces in many parts of the world were depressed by the unrelenting weight of the thrusting ice. At the same time, so much was drawn from the oceans to form these huge glaciers that sea levels around the world fell by three hundred and fifty feet, and large areas of the continental shelf became dry land. This period of the Earth's history had come to be called the Ice Age. In all, about eleven million square miles of land were covered with ice. The Ice Age terminated about fourteen thousand years ago when the ice sheets began to retreat. It took about seven thousand years for the ice to retreat to its present level.

单选题How Deafness Makes It Easier to Hear Most people think of Beethoven"s hearing loss as an obstacle to composing music. However, he produced his most powerful works in the last decade of his life when he was completely deaf. This is one of the most glorious cases of the triumph of will over adversity, but his biographer, Maynard Solomon, takes a different view. Solomon argues that Beethoven"s deafness "heightened" his achievement as a composer. In his deaf world Beethoven could experiment, free from the sounds of the outside world, free to create new forms and harmonies. Hearing loss does not seem to affect the musical ability of musicians who become deaf. They continue to "hear" music with as much, or greater, accuracy than if they were actually hearing it being played. Michael Eagar, who died in 2003, became deaf at the age of 21. He described a phenomenon that happened within three months: "My former musical experiences began to play back to me. I couldn"t differentiate between what I heard and real hearing. After many years, it is still rewarding to listen to these playbacks, to "hear" music which is new to me and to find many quiet accompaniments for all of my moods." How is it that the world we see, touch, hear, and smell is both "out there" and at the same time within us? There is no better example of this connection between external stimulus and internal perception than the cochlear implant (人工耳蜗). No man-made device could replace the ability to hear. However, it might be possible to use the brain"s remarkable power to make sense of the electrical signals the implant produces. When Michael Eagar first "switched on" his cochlear implant, the sounds he heard were not at all clear. Gradually, with much hard work, he began to identify everyday sounds. "The insistent ringing of the telephone became clear almost at once." The primary purpose of the implant is to allow communication with others. When people spoke to Eagar, he heard their voices "coming through like a long-distance telephone call on a poor connection". But when it came to his beloved music, the implant was of no help. When he wanted to appreciate music, Eagar played the piano. He said, "I play the piano as I used to and hear it in my head at the same time. The movement of my fingers and the feel of the keys give added "clarity" to hearing in my head." Cochlear implants allow the deaf to hear again in a way that is not perfect, but which can change their lives. Still, when it comes to musical harmonies, hearing is irrelevant. Even the most amazing cochlear implants would have been useless to Beethoven as he composed his Ninth Symphony at the end of his life.

单选题 U.S. Blacks Hard-hit by Cancer Death rates for cancer are falling for all Americans, but black Americans are still more likely to die of cancer than whites, the American Cancer Society said Monday. In a special report on cancer and blacks, the organization said blacks are usually diagnosed with cancer later than whites, and they are more likely to die of the disease. This could be because of unequal (不平等的) access to medical care, because blacks are more likely to have other diseases as well, and perhaps because of differences in the biology (生物学) of the cancer itself, the report added. "In general, black Americans have less hope of surviving five years after diagnosis than whites for all cancer sites and all stages of diagnosis, "the report said. "In describing cancer statistics for black Americans, this report recognizes that many of the differences associated with race may be caused by unfair social and economic differences and unequal access to medical care." The cancer society said blacks should be encouraged to get check-ups (体格检查) earlier, when cancer is more treatable, and it said more research is needed to see if biological differences play a role. "The new statistics emphasize the continuing importance of wiping out these unfair social differences through public policy and education efforts," the organization said in a statement. But it also noted a drop in cancer death rates. "Cancer death rates in both sexes for all sites combined have dropped greatly among black Americans since 1992, as have incidence rates (发生率)," said the report.

单选题Exercise Weather or not exercise adds (1) the length of life, it is common experience that a certain (2) of regular exercise improves the health and contributes a feeling of well-being. Furthermore, exercise (3) involves play and recreation, and relieves nervous tension and mental fatigue in so doing, is not only pleasant but beneficial. How much and what kind of exercise one should (4) merits careful consideration. The growing child and the normal young man and young woman thrill with the exhilaration of strenuous sports. They fatigue to the (5) of exhaustion but recover promptly with a period of rest. But not so with (6) of middle age and beyond. For them moderation is (7) vital importance. Just how much exercise a person of a given age can safely take is a question (8) to answer. Individual variability is (9) great to permit of generalization. A game of tennis may be perfectly safe for one person of forty but folly for another. The safe limit for exercise (10) on the condition of the heart, the condition of the muscles, the type of exercise, and the regularity with which it is taken. Two general suggestions, however, will (11) as sound advice for anyone. The first is that the condition of the heart and general health should be (12) periodically by careful, thorough physical examinations. The (13) is that exercise should be kept below the point of physical exhaustion. What type of exercise one should (14) depends upon one's physical condition. Young people can safely enjoy vigorous competitive sports, but most older persons do better to limit themselves to less strenuous activities. Walking, swimming, skating are among the sports that one can enjoy and safely participate (15) throughout life. Regularity is important if one is to get the most enjoyment and benefit out of exercise.

单选题Using HIV Virus to Cure Cancer Scientists are planning to use human immunodeficiency (免疫缺陷) virus (HIV), one of mankind's most feared viruses, as a carrier of genes which can fight cancer and a range of diseases that cannot be cured. The experts say HIV has an almost perfect ability to avoid the body's immune (免疫的) defenses, making it ideal for carrying replacement genes into patients' bodies, according to the Observer. A team at the California-based Salk Institute, one of the world's leading research centers on biological sciences, has created a special new breed of HIV and has started negotiations with the U.S. Food and Drug Administration (FDA) to begin clinical gene therapy (治疗) trials this year. The first trials are expected to involve patients suffering from cancers that cannot be cured by surgery although project leader Professor Inder Verma said the HIV technique would have "far wider applications". The plan remains very likely to cause controversy since it involves making use of a virus which has caused more than 22 million deaths around the world in the past two decades. Verma said that the idea of using HIV for a beneficial purpose was "shocking" but the fierce nature of HIV had disappeared by having all six of the potentially deadly genes removed. Illnesses such as various cancers are caused when a gene in a patient's body fails to work properly. In the past two years, breakthroughs in genetics (遗传学) have led gene therapy scientists to try and replace the genes that do not function normally. Unfortunately, the body's immune defenses have been known to attack the modified genes and make them lose their effects before they can start their task and progress in the field has been held up by the lack of a suitable carrier. The HIV virus has the ability to escape from, and then destroy, the immune defense cells designed to protect our bodies and this makes it attractive to scientists as a way of secretly conveying replacement genes into patients' bodies.

单选题He was persuaded to Ugive up/U the idea.

单选题We"ll do all we can to assist you.

单选题These programmes are of immense value to old people.

单选题Deforestation and Desertification(沙漠化) The Sahel zone lies between the Sahara desert and the fertile savannahs (热带大草原) of northern Nigeria and South Sudan. The word sahel comes from Arabic and means marginal or transitional, and this is a good description of these semi-arid (半干旱) lands, which occupy much of the Western African countries of Mall, Mauritania, Niger, and Chad. Unfortunately, over the last century the Sahara desert has steadily crept southwards eating into once productive Sahel lands. United Nations surveys show that over 70 percent of the dry land in agriculture use in Africa has deteriorated over the last 30 years. Droughts have become more severe, the most recent lasting over twenty years in parts of the Sahel region. The same process of desertification is taking place across southern Africa as the Kalahari desert advances into Botswana and parts of South Africa. One of the major causes of this desert advance is poor agricultural land use, driven by the pressures of increasing population. Overgrazing—keeping too many farm animals on the land—means that grasses and other plants cannot recover, and scarce water supplies are exhausted. Overcultivation—trying to grow too many crops on poor land—results in the soil becoming even less fertile and drier, and beginning to break up. Soil erosion (侵蚀) follows, and the land turns into desert. Another cause of desertification is loss of tree cover. Trees are cut down for use as fuel and to clear land for agricultural use. Tree roots help to bind the soil together, to conserve moisture, and to provide a habitat for other plants and animals. When trees are cut down, the soil begins to dry and loosen, wind and rain erosion increase, other plant species die, and eventually the fertile topsoil may be almost entirely lost, leaving only bare rock and dust. The effects of loss of topsoil and increased drought are irreversible. They are, however, preventable. Careful conservation of tree cover and sustainable agricultural land use have been shown to halt deterioration of soils and lessen the effects of shortage of rainfall. One project in Kita in south-west Mall funded by UNDP has involved local communities in sustainable management of forest, while at the same time providing a viable (有活力的) agricultural economy. This may be a model for similar projects in other West African countries.

单选题We cannot compel you to do it, but we think you should.

单选题Coming Soon to a Theater near You! What are special effects? Do you enjoy movies that use a lot of special effects?. Dinosaurs (恐龙) from the distant past! Space battles from the distant future! There has been a revolution in special effects, and it has transformed the movies we see. The revolution began in the mid-1970s with George Lucas's Star Wars, a film that stunned (使震惊) audiences. That revolution continues to the present with dramatic changes in special effects technology. The company behind these changes is Lucas's Industrial Light ＆ Magic (ILM). And the man behind the company is Dennis Muren, who has worked with Lucas since Star Wars. Muren's interest in special effects began very early. At the age of 6, he was photographing toy dinosaurs and spaceships. At 10, he had an 8 millimeter movie camera and was making these things move through stop motion. (Stop-motion is a process in which objects are shot with a camera, moved slightly, shot again, and so on. When the shots are put together, the objects appear to move.) Talk to Muren and you'll understand what ILM is all about; taking on new challenges. By 1989, Muren decided he had pushed the old technology as far as it would go. He saw computer graphics(图像)(CG)technology as the wave of the future and took a year off the master it. With CG technology, images can be scanned into a computer for processing, for example, and many separate shots can be combined into a single image. CG technology has now reached the point, Muren says, where special effects can be used to do just about anything so that movies can tell stories better than ever before. The huge success of Jurassic Park and its sequel (续集), The Lost World, the stars of which were computer-generated dinosaurs, suggests that this may very well be true.

单选题During the 1800's and early 1900's, new academic disciplines such as chemistry and physics made great {{U}}headway{{/U}}.

单选题He"s going to set off on a journey to New York.

单选题These programs are of {{U}}immense{{/U}} value to old people. A. natural B. fatal C. tiny D. enormous

单选题Mr. Henley has accelerated his sale of shares over the past year. A. held B. increased C. expected D. offered

单选题Data from Voyager II have presented astronomers with a puzzle about why our outermost planet exists. A. problem B. mystery C. question D. point

单选题The program, run by psychotherapists Cosette Dawna Rae and Hilarie Cash, is located in Rae's house, where her husband and son also reside. There's room for six patients, but during Alexander's treatment, he is the only one at the facility. He is given a regular schedule, with outdoor activities (including carpentry projects or caring for chickens and goats) plotted throughout the day, plus chores and meals. Rae says the program is designed to mimic what life will be like once patients return home--downtime is built into the routine, so people can learn to cope with boredom. Alexander spends some of that time running--when he first got to the facility, he expressed all interest in running, so Rae and Cash set him up with a local trainer, who now takes him on regular jogs. Alexander also has daily counseling sessions with Rae ,where they discuss his long- term goals, and even work on a plan for a tutoring business he hopes to start. Once a week, he has a therapy session with Cash, a specialist in video game and Internet addiction. Downtime was built into the routine during whichA. Alexander read his favorite book.B. Alexander learned to deal with boredom.C. Alexander rested to recover from fatigue.D. Alexander started to think about his futur