单选题My friend"s reply was courteous but firm.

单选题The Television Camera The television camera is rather like the human eye. Both the eye and the camera have a lens, and both produce a picture on a screen. In each case the picture is made up of millions of spots of light. Let us see how the eye works. When we look at an object, a person, a house, or whatever it may be, we do not see all the details of the object in one piece. We imagine that we do, but this is not the case. In fact, the eye builds up the picture for us in our brain, which controls our sight, in millions of separate parts, and although we do not realize it, all these details are seen separately. This is what happens when we look at something. Beams of light of different degrees of intensity, reflected from all parts of the object, strike the lens of the eye. The lens then gathers together the spots of light from these beams and focuses them on to a light-sensitive plate, the retina, at the back of the eyeball. In this way an image of the object is produced on the retina in the form of a pattern of lights. The retina contains millions of minute light-sensitive elements, each of which is separately connected to the brain by a tiny fiber in the optic nerve. These nerve fibers, working independently, pick out minute details from the image on the retina and turn the small spots of light into nerve impulses of different strengths. They then transmit these impulses to the brain. They do this all at the same time. All the details of the image are fed to the brain, and, so we have taught our brain to add them together correctly. We see a clear picture of the object as a whole. Television, which means vision at a distance, operates on a similar principle. A television picture is built up in thousands of separate parts. Beams of light reflected from the subject being televised strike the lens of the television camera, which corresponds to the lens of the eye. The camera lens gathers together the spots of light from these beams and focuses an image of the subject on to a plate, the surface of which is coated with millions of photo-electric elements sensitive to light. The spots of light forming the image on the plate cannot be transmitted as light. So they are temporarily converted by an electronic device into millions of electrical impulses; that is, into charges of electricity.' These electrical impulses are then sent through space on a wireless wave to the homes of the viewers. They are picked up by the aerials and conveyed to the receivers the to television sets. There, they are finally converted back into the spots of light that make up the picture on the television screen.

单选题She always finds fault with everything.

单选题 下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。 {{B}}Migrant workers{{/B}} In the past twenty years, there has been an increasing tendency for workers to move from one country to another.{{U}} (51) {{/U}}some newly independent countries have understandably restricted most jobs to local people, others have attracted and welcomed migrant workers. This is particularly the case in the Middle East,{{U}} (52) {{/U}}increased oil incomes have enabled many countries to{{U}} (53) {{/U}}outsiders to improve local facilities.{{U}} (54) {{/U}}the Middle East has attracted oil-workers from the U. s. A. and Europe. It has brought in construction workers and technicians from many countries,{{U}} (55) {{/U}} South Korea and Japan. In view of the difficult living and working conditions in the Middle East, it is not{{U}} (56) {{/U}}that the pay is high to attract suitable workers. Many engineers and technicians can earn at least{{U}} (57) {{/U}} money in the Middle East as they can in their own country, and this is a major attraction. An allied benefit is the low taxation or complete lack of it. This increases the net amount of pay received by visiting workers and is very popular with them. Sometimes a disadvantage has a compensating advantage.{{U}} (58) {{/U}}, the difficult living conditions often lead to increased friendship when workers have to depend on each other{{U}} (59) {{/U}}safety and comfort.{{U}} (60) {{/U}}, many migrant workers can save large sums of money partly{{U}} (61) {{/U}} the lack of entertainment facilities. The work is often complex and full of problems but this merely presents greater challenge to engineers who prefer to find solutions{{U}} (62) {{/U}}problems rather than do routine work in their home country. One major problem which{{U}} (63) {{/U}}migrant workers in the Middle East is that their jobs are temporary ones. They are nearly always on contract, so it is not easy for them to plan ahead with great confidence. This is to be expected since no country welcomes a large number of foreign workers as permanent residents.{{U}} (64) {{/U}}, migrant workers accept this disadvantage, along with others, because of the{{U}} (65) {{/U}}financial benefits which they receive.

单选题A new system of quality control was {{U}}brought in{{/U}} to overcome the defects in the firm's products.

单选题Recent studies have posed the question as to whether there is a link between thing and that person.A. supposedB. pogedC. arousedD. raised

单选题 Ulcers Even though ulcers appear to run in families, lifestyle plays more of a role than genetic factors in causing the illness, according to a report in the April 13th Journal of Internal Medicine. In particular, smoking and stress in men and the regular use of pain releasing medicines in women were linked with an increased risk of developing all ulcers. Overall, 61% of ulcer risk appears to be due to environmental factors, such as smoking, and the remaining 39% is due to genes according to Dr. Ismo Raiha Of the University of Turky and colleagues at the University of Helsinki, Finland. Some researchers had suggested that families may spread Helicobacteria pylori, the bacteria that can cause ulcers. However, the new study suggests this is unlikely, according to the report. Raiha and colleagues studied data from more than 13,000 pairs of twins "to examine the roles of genetic and environmental factors in the origin of peptic ulcer disease", they explain. Both twins were more likely to develop an ulcer if the pair were genetically the same as compared with a pair of fraternal twins, suggesting that there must be some genetic susceptibility to ulcer development. However, the risk was no greater in twins living together compared with twins living apart, suggesting that shared exposure to H. pylori (幽门螺旋菌) was not to blame. "Environmental effects were not due to factors shared by family members, and they were related to smoking and stress in men and the use of analgesics in women," the authors wrote. "The minor effects of shared environment to disease liability do not support the concept that the grouping of risk factors, such as H. pylori infection, would explain the genetic factor of peptic ulcer disease, "they concluded.

单选题The defeated troops were ordered to scatter and then {{U}}concentrate{{/U}} fifty miles to the south.

单选题Silk, although it is considered a delicate fabric, is in fact very strong, but it is adversely affected by sunlight.A. softB. sheerC. fragileD. refined

单选题 下面有3篇短文，每篇短文后有5道题，每道题后面有4个选项。请仔细阅读短文并根据短文内容回答其后面的问题，从4个选项中选择1个最佳答案。{{B}}第一篇{{/B}} {{B}} US Blacks Hard-hit by Cancer{{/B}} Death rates from 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 access to medical care, because blacks are more likely to have other diseases like diabetes as well, and perhaps because of differences in the biology of the cancer itself, the report added. "In general, African Americans have less likelihood 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 African Americans, this report recognizes that socioeconomic disparities and unequal access to medical care may underlie many of the differences associated with race." The cancer society said blacks should be encouraged to get check-ups earlier, when cancer is more treatable, and it said more research was needed to see if biological differences play a role. "The new statistics emphasize the continuing importance of eliminating these social disparities 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 declined substantially among African Americans since 1992, as have incidence rates," says the report. "Increased efforts to improve economic conditions in combination with education about the relationship of lifestyle choices to cancer could further reduce the burden of cancer among African Americans." About 36 million Americans describe themselves as black, representing about 12 percent of the population.

单选题China does a lot of trade with many countries. A. a great deal of B. a great many of C. a large number of D. a great level of

单选题Medicine depends on other fields for basic information, particularly some of their specializec branches.

单选题Common Problems, Common Solutions The chances are that you made up your mind about smoking a long time ago—and decided it"s not for you. The chances are equally good that you know a lot of smokers—there are, after all about 60 million of them, work with them, play with them, and get along with them very well. And finally it"s a pretty safe bet that you"re open-minded and interested in all the various issues about smokers and nonsmokers-or you wouldn"t be reading this. And those three things make you incredibly important today. Because they mean that yours is the voice—not the smoker"s—and not the anti-smoker"s— that will determine how much of society"s efforts should go into building walls that separate us and how much into the search for solutions that bring us together. For one tragic result of the emphasis on building walls is the diversion of millions of dollars from scientific research on the causes and cures of diseases which, when all is said and done, still strike the nonsmoker as well as the smoker. One prominent health organization, to cite but a single instance, now spends 28 cents of every publicly-contributed dollar on "education"(much of it in anti-smoking propaganda) and only 2 cents on research. There will always be some who want to build walls, who want to separate people from people, and up to a point, even these may serve society. The anti-smoking wall-builders have, to give them their due, helped to make us all more keenly aware of choice. But our guess, and certainly our hope, is that you are among the far greater number who know that walls are only temporary at best, and that over the long run, we can serve society"s interests better by working together in mutual accommodation. Whatever virtue walls may have, they can never move our society toward fundamental solutions. People who work together on common problems, common solutions, can.

单选题The April edition ({{U}}covering{{/U}} copies, overseas deliveries and office cleaning) is now available.

单选题A neutron is so tiny that it would take ten trillion of them to cover a square inch.

单选题Stress and Heart Disease If you often feel angry and overwhelmed, like the stress in your life is spinning out of control, then you may be hurting your heart. If you don"t want to break your own heart, you need to learn to take charge of your life where you can—and recognize there are many things beyond your control. So says Dr. Robert S. Eliot, author of a new book titled From Stress to Strength: How to Lighten Your Load and Save Your Life . He"s a clinical professor of medicine at the University of Nebraska. Eliot says there are people in this world whom he calls "hot reactors". For these people, being tense may cause tremendous and rapid increases in their blood pressure. Eliot says researchers have found that stressed people have higher cholesterol levels, among other things. "We"ve done years of work in showing that excess alarm or stress chemicals can literally burst heart muscle fibers. When that happens it happens very quickly, within five minutes. It creates many short circuits, and that causes crazy heart rhythms. The heart beats like a bag of worms instead of a pump. And when that happens, we can"t live." Eliot, 64, suffered a heart attack at age 44. He attributes some of the cause to stress. For years he was a "hot reactor". On the exterior, he was cool, calm and collected, but on the interior, stress was killing him. He"s now doing very well. The main predictors of destructive levels of stress are the FUD factors—fear, uncertainty and doubt— together with perceived lack of control, he says. For many people, the root of their stress is anger, and the trick is to find out where the anger is coming from. "Does the anger come from a feeling that everything must be perfect?" Eliot asks. One step to calming down is to recognize you have this tendency. Learn to be less hostile by changing some of your attitudes and negative thinking. Eliot recommends taking charge of your life. "If there is one word that should be substituted for stress, it"s control. Instead of the FUD factors, what you want is the NICE factors—new, interesting, challenging experiences." "You have to decide what parts of your life you can control," he says. "Stop where you are on your trail and say, "I"m going to get my compass out and find out what I need to do."" He suggests that people write down the six things in their lives that they feel are the most important things they"d like to achieve. Ben Franklin did it at age 32. "He wrote down things like being a better father, being a better husband, being financially independent, being stimulated intellectually and remaining even-tempered—he wasn"t good at that." From Eliot"s viewpoint, the other key to controlling stress is to realize that there are other troublesome parts of your life over which you can have little or no control—like the economyand politicians.

单选题The conference explored the possibility of closer trade links. A. rejected B. investigated C. proposed D. exposed

单选题This text is too difficult to comprehend.

单选题Almost all economists agree that nations gain by trading with one another.

单选题From 1994 to 1998 the number of Americans who had donated a kidney reached 244.