单选题I can't make it because of a {{U}}previous{{/U}} engagement.

单选题According to the science of aerodynamics,the shape of an object influences the amount of drag created by air flowing around it.

单选题Would you please call my husband as soon as possible?

单选题 Effects of Environmental Pollution If pollution continues to increase at the present rate, formation of aerosols (浮质) in the atmosphere will cause the onset (开始) of an ice age in about fifty years' time. This conclusion, reached by Dr. S.I. Rasool and Dr. S.H. Schneider of the United States Goddard Space Flight Centre, answers the apparently conflicting questions of whether an increase in the carbon dioxide (二氧化碳) content of the atmosphere will cause the Earth to warm up or increasing the aerosol content will cause it to cool down. The Americans have shown conclusively that the aerosol question is dominant. Two specters haunting conservationists have been the prospect that environmental pollution might lead to the planet's becoming unbearably hot or cold. One of these ghosts has now been laid. Because it seems that even an increase in the amount of carbon dioxide in the atmosphere to eight times its present value will produce an increase in temperature of only 2℃, which would take place over several thousand years. But the other problem now looms larger than ever. Aerosols are collections of small liquid or solid particles dispersed in air or some other medium. The particles are all so tiny that each is composed of only a few hundred atoms. Because of this they can float in the air for a very long time. Perhaps the most commonly experienced aerosol is industrial smog (烟雾) of the kind that plagued London in the 1950s and is an even greater problem in Los Angeles today. These collections of aerosols reflect the Sun's heat and thereby cause the Earth to cool. Dr. Rasool and Dr. Schneider have calculated the exact effect of a dust aerosol layer just above the Earth's surface in the temperature of the planet. As the layer builds up, the present delicate balance between the amount of heat absorbed from the Sun and the amount radiated from the Earth is disturbed. The aerosol layer not only reflects much of the Sun's light but also transmits the infrared (红外线的) radiation from below. So, while the heat input to the surface drops, the loss of heat remains high until the planet cools to a new balanced state. Within fifty years, if no steps are taken to stop the spread of aerosols in the atmosphere, a cooling of the Earth by as much as 3.5℃ seems inevitable. If that lasts for only a few years it would start another ice age, and because the growing ice caps at each pole would themselves reflect much of the Sun's radiation it would probably continue to develop even if the aerosol layer were destroyed. The only bright spot in this gloomy forecast lies in the hope expressed by Dr. Rasool and Dr. Schneider that nuclear power may replace fossil fuels in time to prevent the aerosol content of the atmosphere from becoming critical.

单选题Cooking Off Fumes Cause Tumor The leading cause of lung cancer among women in the city was cooking oil fumes while men are more likely to develop the disease from smoking, said medical experts after a five-year research study. Doctors announced the results yesterday with analysis on some new tendencies in lung cancer. They said patients are younger, especially women. According to the Shanghai Tumor Research Institute, more local residents die of lung cancer in the city than anything else. Following breast cancer, it has the second-highest incidence rate. "An unhealthy lifestyle is a very important reason for lung cancer," said Dr. He Yumin from Shanghai Minshen Traditional Chinese Medicine Tumor Diagnosis and Treatment Center. He followed 2,276 lung cancer patients for five years. Among them, 1,483 were male. Smoking causes 70 percent of cases among men while only 18 percent of female patients developed cancer from smoking or inhaling second-hand smoke, according to the report. However, more than 60 percent of women with the disease had long-term, close contact with strong oil fumes from cooking and complained about irritated eyes and throat. About 32 percent of women fried foods in boiling oil in unventilated kitchens and about 25 percent of women"s bedrooms were adjacent to the kitchen. However, local women were surprised to learn cooking oil fumes could lead to cancer. Some claimed they may change food preparation methods. "Unless my family and I don"t eat at home every day, I must stay in the kitchen to cook," said Xu Li, a 45-year-old local woman. "I know the fumes are bad for the skin, but it is the first time I heard that it can result in lung cancer. I have already started frying less." Doctors said women"s lung cancer had few links to personal health and physical condition, but was closely related to family cancer history, unhealthy dietary habits and weak immune systems. Other experts agreed with He. "Smoking is by far the biggest cause of lung cancer for men," said Dr. Tan Binyong, honorary president of the Respiratory Disease Institute at Fudan University"s Medical College. "It"s true that second-hand smoke and cooking fumes are the main causes among women." He"s research also warned people not to stand near of stalls selling fried foods due to the poor quality of oils used. The chance of catching lung cancer is three times higher if exposed to the fume for a long time, experts said.

单选题Medal's theories on heredity

单选题I sat near the entrance for a long time expecting him, but he didn't arrive.A. waiting forB. waitingC. looking forD. watching

单选题Sleeping People who sleep for more than eight hours a night do not live as long as those who sleep for six hours, according to the biggest study yet into sleep patterns and mortality(死亡率). Scientists have no explanation for the findings and do not know if they mean people who like a lie. in(睡懒觉)Can extend their lives by sleeping less. Although it is a common belief that sleeping for at least eight hours a night is vital for health and well—being. the six. year study involving more than 1. 1 million Americans older than 30 found that those who slept for less than eight hours were far from doing themselves any long—term harm。 "Individuals who now average 6. 5 hours of sleep a night Can be reassured that this is a safe amount of sleep. From a health standpoint。there is no reason to sleep longer," said Daniel Kripke , a professor of psychiatry(精神病学)at the University of California, San Diego. Dr. Kripke said. "We don't know if long sleep periods lead to death. Additional studies are needed to determine if setting your alarm clock earlier will actually improve your health. " The scientists. who were funded by the American Cancer Society, found at the best survival rates were among the men and women who slept for seven hours a night. Those who slept for eight hours were 12 per cent more likely to die during the six—year period of the study, when other factors such as diet and smoking were taken into account. Even those who spent a mere five hours a night in bed lived longer than those who slept eight or more hours. However, an increasing death rate was found among those who slept for less than five hours. Dr. Kripke said. "Previous sleep studies have indicated that both short-and long-duration(持续时间)sleep had higher mortality rates. However, none of those studies were large enough to distinguish the difference between seven and eight hours a night, until flow. /

单选题He's spent years cultivating a knowledge of art. A. sharing B. using C. denying D. developing

单选题The unprecedented interest in the cure of cancer was aroused by

单选题He works in a sports centre instructing people in the use of the gym equipment.A. helpingB. teachingC. informingD. ordering

单选题The debate over spanking goes back many years, but the essential question often evades (同避) discussion: does spanking actually work? In the short term, yes. You can correct immediate misbehavior with a slap or two on the rear - end or hand. But what about the long - term impact? Can spanking lead to permanent, hidden scars on children years later? With a slap or two on the butt or hand of the child, a parent canA. correct immediate misbehavior.B. leave permanent scars on the bedy.C. lead the child to the fight course of life.D. evade discussion of what's wron

单选题Your hair is so tangled that it looks as if it has not been combed for a month. A. mix up B. moisturizing C. disordered D. settle

单选题 阅读下面这篇短文，短文后列出7个句子，请根据短文的内容对每个句子做出判断。 {{B}} Kitchen Design{{/B}} Over the years economic, social and technological factors have influenced the design of kitchens. Since it is often used simultaneously by both family members as well as guests, the kitchen requires not only a glamorous look but a practical one. Also, the design elements must meet the needs of the modern family. Environmental concerns have had an enormous impact on kitchen design. This concern includes recycling of household materials, as well as energy efficient appliances and the purity of both water and air. Research shows that up to 85 percent of the population is concerned about what might be in their drinking water. They are also often dissatisfied with the taste and odor of what comes out of their tap. This is why it's important to consider adding a water filter system. The character of today's kitchen is very different from the way it was thirty years ago. There's more sophistication in food preparation, and more technological help with cooking and clean up. When choosing cabinets, first consider the style. Use the architectural style of your house as a guide. Because cabinets are a big investment, it is best to choose quality. Popular styles in kitchen cabinets are framed panel doors with raised or recessed panels of wood, cabinet fronts with glass panes, or simple slab doors in a rich painted or laminated finish. Cabinet pulls, handles and knobs are offered in a myriad of designs and finishes. Treat hardware as jewelry and don't be afraid to mix and match styles. Because many of today's kitchens consist of two or more cooks sharing in the meal preparation, there is a need for more counter space, cooktops and sinks. Altough lifestyles are changing, the primary function of the kitchen as an area for preparing food has remained unchanged. The sink 10 remains one of the most used areas in the kitchen as well as an important decorative statement. Appliance technology is moving at a very fast pace. Choosing what type of appliances as well as how many will depend on several factors such as how often and how much you cook and the size of you kitchen. Don't limit yourself to one of each kind of appliance. You can have a refrigerator in one place and a freezer in a separate area or two sets of cooktops, one on the counter next to the wall oven and one on an island. You can even have two sets of cooktops, one on the counter next to the wall oven and one on an island. You can even have two dishwashers if size and budget requirs and permit-think of it as saving time in the long run.

单选题More about Alzheimer's Disease Scientists have developed skin tests that may be used in the future to identify people with Alzheimer's disease and may ultimately allow physicians to predict who is at risk of getting this neurological disorder. The only current means of diagnosing the disease in a living patient is a long and expensive series of tests that eliminate every other cause of dementia. "Since Alois Alzheimer described the disease nearly a century ago, people have been trying to find a way to accurately diagnose it in its early stages, " said Patricia Grady, acting director of the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland. "This discovery, if confirmed, could prove a big step forward in our efforts to deal with and understand the disease. " Alzheimer's is the single greatest cause of mental deterioration in older people, affecting between 2.5 million and 4 million people in the United States alone. The devastating disorder gradually destroys memory and the ability to function, and eventually causes death. There is currently no known treatment for the disease. Researches discovered that the skin cells of Alzheimer's patients have defects that interfere with their ability to regulate the flow of potassium in and out of the cells. The fact that the cell defects are present in the skin suggests that Alzheimer's results from physiological changes throughout the body, and that dementia may be the first noticeable effect of these changes as the defects affect the cells in the brain, scientists said. The flow of potassium is especially critical in cells responsible for memory formation. The scientists also found two other defects that affect the cells' supply of calcium, another critical element. One test developed by researches calls for growing skin cells in a laboratory culture and then testing them with an electrical detector to determine if the microscopic tunnels that govern the flow of potassium are open. Open potassium channels create a unique electrical signature. A. spokesman for the Alzheimer's Association said that if the validity of the diagnostic test can be proven it would be an important development, but cautioned that other promising tests for Alzheimer's have been disappointing.

单选题I am heartily grateful to your help.

单选题Nerve signals may travel through nerve or muscle fibers at speeds as high as two hundred miles per hour.

单选题They have the capability to destroy the enemy in a few days.

单选题We should {{U}}contemplated{{/U}} the problem from all sides. A. deliberated B. thought C. described D. designed

单选题El Nino While some forecasting methods had limited SUCCESS predicting the 1997 E1 Nino a few months in advance, the Columbia University researchers say their method call predict large E1 Nonevents up to two years in advance. That would be good news for governments, farmers and others seeking to plan for the droughts and heavy rainfall that E1 Nino can produce in various parts of the world. Using a computer the researchers matched sea-surface temperatures to later E1 Ni?o occurrences between 1980 and 2000 and were then able to anticipate E1 Nino events dating back to 1857, using prior sea-surface temperatures. The results were reported in the latest issue of the journal Nature. The researchers say their method is not perfect, but Bryan C. Weare, a meteorologist at the University of California, Davis, who was not involved in the work, said it "suggests E1 Nino is indeed predictable." "This will probably convince others to search around more for even better methods." Said Weare. He added that the new method "makes it possible to predict E1 Nino at long lead times."Other models also use sea-surface temperatures, but they have not looked as far back because they need other data, which is only available for recent decades, Weare said. The ability to predict the warming and cooling of the Pacific is of immense importance. The 1997 EL Nino, for example, caused an estimated $20 billion in damage worldwide, offset by beneficial effects in other areas. The 1877 E1 Nino, meanwhile, coincided with a failure of the Indian monsoon and a famine that killed perhaps 40 million in India and China, prompting the development of seasonal forecasting, Anderson said. When E1 Nino hit in 1991 and 1997. 200 million people were affected by flooding in Chinaalone, according to a 2002 United Nations report. While predicting smaller E1 Nino events remains tricky. The ability to predict larger ones should be increased to at least a year if the new method is confirmed. E1 Nino tends to develop between April and June and reaches its peak between December and February. The warming tends to last between 9 and 12 months and occurs every two to seven years. The new forecasting method does not predict any major E1 Nino events in the next two years,although a weak warming toward the end of this year is possible.