单选题There is no question that the old style of air pollution could kill people. In one week following the infamous "peasouper" fog in December 1952, 4, 700 people died in London. Most of these people were elderly and already had heart or lung diseases. A series of these killer fogs eventually led to the British Parliament passing the Clean Air Act which restricted the burning of coal. Fortunately the effect of smog on the lungs is not so dramatic. Scientists have now conducted a number of laboratory experiments in which volunteers are exposed to ozone inside a steel chamber for a few hours. Even at quite low concentrations there is a reversible fall in lung function, an increase in the irritability of the lungs and evidence of airway inflammation (发炎). Although irritable and inflamed lungs are particularly seen in people with asthma (哮喘) and other lung diseases, these effects of ozone also occur in healthy subjects. Similar changes are also seen after exposure to nitrogen dioxide, although there is some disagreement about the concentration at which they occur. Other studies have found that people living in areas with high levels of pollution have more symptoms and worse lung function than those living in areas with clean air. Groups of children attending school camps show falls in lung function even at quite low concentrations of ozone. There is also a relationship between ozone levels and hospital admissions for asthma, both in North America and Australia. It is suspected that long-term exposure to smog may result in chronic bronchitis (支气管炎) and emphysema (肺气肿), but this has yet to be proven. Recently an association has been found between the levels of particles in the air and death rates in North American cities. The reason for this association is not understood and as yet there is no evidence this occurs in Australia. However, we do know that hazy days are associated with more asthma attacks in children.

单选题Don' tU meddle /Uin her affairs, and in fact, she can attack the problem and solve it quickly herself.

单选题The economy in this region has been stagnant for a long time and no signs of recovery have ______ till now. A. shown up B. kept up C. picked up D. made for

单选题You didn"t put on more clothes; otherwise you ______ cold.

单选题Pan of his general thrift is to be meticulous in verifying monthly expenses.

单选题To some people, the greatest pleasure of life is to spend their time at home watching TV and ______ their pets. A.stroking B.desiring C.modeling D.flattering

单选题Small, pink and very ugly. Hardly the qualities of a star, but they describe the deformed mouse that was the media darling at a recent science exhibition in Beijing. With a complex tissue structure in the shape of a human ear grafted on to its back, the rosy rodent was a stunning symbol of the serious strides China is making in the field of biotechnology. China is fast applying the latest life-science techniques learned from the West m aggressively pursue genome research. It's establishing its own centers of technical excellence to build a scientific base to compete directly with the United States and Europe. With a plentiful supply of smart young scientists at home and lots of interest abroad biotechnology is on the brink of a boom in China and in the view of foreign scientists, Beijing is playing a clever hand, maximizing the opportunities open to them. For the moment, the cooperation exists mostly with Europe and the U. S. But Asia's other biotech leaders, Japan, Singapore and Korea, also are recognizing China's potential as an attractive low-cost base to conduct research. These partnerships--and China's advancement in the field of biotechnology--could help benefit the rest of Asia: China's rapid progress in improving crop yields will address food-security concerns in the region. In addition, China is more likely to focus on developing cheap technology that its predominantly poor population--and those of other Asian countries--can afford. There remain, however, serious barriers to the development of a strong biotech industry. Among them are a poor domestic legal framework, weak enforcement of intellectual-property rights and loose adherence to international standards. China is a signatory of the International Bio Safety Protocol, which should mean adherence to global standards governing the conduct of field trims. But some observers are skeptical. "The regulations look good, but I haven't met one scientist who believes they are being fully adhered to," says a European science analyst. If shortcuts are taken, then some of the recent scientific achievements trumpeted in the official press may never make it to market. But no matter how strict lab tests are, other problems lie in wait. For example, there is a number of tasks it would take years to fulfill in the patents office, says one lawyer, leaving innovators with little protection if they take a product to market in China.

单选题Some women, particularly those over 35 years of age, seem to be more ______ more serious problems such as clots in veins if they smoke heavily.

单选题Archaeology as a profession faces two major problems. First.it is the poorest of the poor. Only paltry sums are available for excavating and even less is available for publishing the results and preserving the sites once excavated. Yet archaeologists deal with priceless objects every day. Second, there is the problem of illegal excavation, resulting in museum-quality pieces being sold to the highest bidder. I would like to make an outrageous suggestion that would at one stroke provide funds for archaeology and reduce the amount of illegal digging. I would propose that scientific archaeological expeditions and governmental authorities sell excavated artifacts on the open market Such sales would provide substantial funds for the excavation and preservation of archaeological sites and the publication of results. At the same time, they would break the illegal excavator's grip on the market, thereby decreasing the inducement to engage in illegal activities. You might object that professionals excavate to acquire knowledge, not money. Moreover, ancient artifacts are part of our global cultural heritage, which should be available for all to appreciate, not sold to the highest bidder. I agree. Sell nothing that has unique artistic merit or scientific value. But, you might reply, everything that comes out of the ground has scientific value. Here we part company. Theoretically, you may be correct in claming that every artifact has potential scientific value. Practically, you are wrong. I refer to the thousand pottery vessels and ancient lamps that are essentially duplicates of one another. In one small excavation in Cyprus, archaeologists recently uncovered 2000 virtually indistinguishable small jugs in a single courtyard. Even precious royal seal impressions known as 1' melekh handles have been found in a-bundance------more than 4000 examples so far. The basements of museums are simply not large enough to store the artifacts that are likely to be discovered in the future. There is not enough money even to catalogue the finds;as a result, hey cannot be found a-gain and become as inaccessible as if they had never been discovered Indeed, with the help of a computer, sold artifacts could be more accessible than are the pieces stored in bulging museum basements. Prior to sale, each could be photographed and the list of the purchasers could be maintained on the computer. A purchaser could even be required to agree to return the piece if it should become needed for scientific purposes.

单选题The most convincing evidence for the importance of adult influence on a child's intelligence comes from a study of "at risk" children. Ramey and Frances Campbell of the University of North Carolina 61 with children born into poverty-line households. The children entered the study by four months 62 age. During the study, one group spent the day in a center where teachers used games and songs to 63 the infants. Another group had no such 64 , but they were given nutritional supplements in 65 . During preschool years the children in the early-education group showed IQ advantages often to 20 points. The highest-risk children showed the 66 gains, and at age 15 they had higher reading and math scores. What 67 for these gains? Ramey and other scientists say early childhood experiences 68 brain growth. An infant is bom 69 billions of brain cells called neurons. Some are wired to other cells before birth to regulate the 70 of life, such as heartbeat and breathing. Others are waiting to be wired to 71 him or her interpret and respond to the outside world. Experience dictates the hookups. As the child 72 , cells reach out and set up pathways to other cells needed to determine a 73 . For instance, the neurons in the eye send branches to the 74 cortex, which interprets 75 eye sees and, via other branches, 76 the person to react to what is seen. Each time an experience is repeated, the 77 are strengthened. The first two years of life are an explosion of brain 78 and connections. By age two the 79 has more than 300 trillion connections. At the same time, cells that aren't being connected or used are being 80 .

单选题 4 Linguists have understood for decades that language and thought are closely relat- ed. Humans construct reality using thought and express these thoughts through the use of language. Edward Sapir and his student Benjamin Whorl are credited with developing the most relevant explanation outlining the relationship between thought and language, the Sapir-Whorf Hypothesis. The hypothesis consists of two parts, linguistic relativity and lin guistic determinism. Supporters of linguistic relativity assume that culture is shaped by lan guage. Terwilliger defines linguistic determinism as the process by which "the functions of one's mind are determined by the nature of the language which one speaks. " In simpler terms, the thoughts that we construct are based upon the language that we speak and the words that we use. In its strongest sense, linguistic determinism can be interpreted as meaning that language determines thought. In its weakest sense, language partially influ ences thought. Whorl was careful to avoid authoritative statements which would perma nently commit him to particular position. Because of the broad nature of his statements, it is difficult to distinguish exactly to what extent Whorl believes that language determines thought. Heated debate among mod ern linguists demonstrates that disagreement exists about the accuracy and correctness of Whorf's studies and of the actual level of influence of language on thought processes. The Sapir-Whorf Hypothesis essentially consists of two distinct statements connecting the relation of thought and language. Whorl believes that humans may be able to think only about objects, processes, and conditions that have language associated with them. The Sapir-Whorf Hypothesis also explains the relationship between different languages (French, English, German, Chinese, and so on) and thought. Whorl demonstrated that culture is largely determined by language. Different cultures perceive the world in different ways. Culturally essential objects, conditions and processes usually are defined by a pleth ora of words, while things that cultures perceive as unimportant are usually assigned one or two words. Whorl developed this theory while studying the Hopi Indian tribe. Whorl was amazed that the Hopi language has no words for past, present, and future. The Hopi have only one word for flying objects. A dragonfly, an airplane, and a pilot are defined using the same word. Whorl questioned whether or not the Hopi view the world differently than western peoples. After further interpretation and analysis he concluded that the Hopi have a sense for the continuum of time despite having no words to specifically describe past, present, and future. It is commonly believed that the Sapir-Whorf Hypothesis possesses some truth, but the extent to which it is applicable to all situations is questioned. Linguists generally sup port a "strong" or a "weak" interpretation. Linguists who study the hypothesis tend to cite examples that support their beliefs but are unable or unwilling to refute the opposing arguments. Examples exist that strengthen the arguments of everyone who studies the hy pothesis. Nobody has gained significant ground in proving or refuting the hypothesis be cause the definitions of Sapir and Whorl are very vague and incomplete, leaving room for a significant amount of interpretation.

单选题The United States was trying hard to smoke the enemy out of the holesin the target country．

单选题______ students should be motivated by a keen interest in theatre and should have some familiarity with plays in production.

单选题We ______ the radio signals for help from the plane.

单选题Which of the following is True about affirmative action according to the text?

单选题Obviously, the per capita income of a country depends on many things, and any statistical test that does not take account of all important determinants is misspecified, and thus must be used only for descriptive and heuristic purposes. It is nonetheless interesting--and for many people surprising--to find that there is a positive and even a statistically significant relationship between these two variables: the greater the number of people per square kilometer the higher the per capita income. The law of diminishing returns is not invariably true. It would be absurd to suppose that a larger endowment of land ipso facto makes a country poorer. This consideration by itself would, of course, call for a negative sign on population density. Thus, it is interesting to ask what might account for the "wrong" sign and think of what statistical tests should ultimately be done. Clearly there is a simultaneous two-way relationship between population density and per capita income; the level of per capita income affects population growth just as population, by increasing the labor force, affects per capita income. The argument offered here suggests that perhaps countries with better economic policies and institutions come to have higher per capita incomes than countries with inferior policies and institutions, and that these higher incomes bring about a higher population growth through more immigration and lower death raters. In this way, the effects of better institutions and policies in raising per capita income swamps the tendency of diminishing returns to labor to reduce it. This hypothesis may also explain why many empirical studies have not been able to show a negative association between the rate of population growth and increases in per capita income. One reason why the ratio of natural resources to population does not account for variations in per capita income is that most economic activity can now readily be separated from deposits of raw material and arable land. Over time, transportation technologies have certainly improved, and products that have a high value in relation to their weight, such as most services and manufactured goods like computers and airplanes, may have become more important. The Silicon Valley is not important for the manufacturing of computers because of the deposits of silicon, and London and Zurich are not great banking centers because of fertile land. Even casual observation suggests that most modem manufacturing and service exports are not closely related to natural resources. Western Europe does not now have a high ratio of natural resources to population, but it is very important in the export of manufactures and services. In a parallel way, the striking success of Japan, Hong Kong, and Singapore, with relatively few natural resources per capita, cannot be explained by reliance thereon.

单选题An investigation of the circulation of blood in the eyes of diver has produced the strongest evidence that tissue damage caused by diving is more common and more severe than had been previously thought. Of the 26 professional divers studied, all had abnormal retinas. None of the divers taking part in the study had visual problems as a result of their damaged retinas but Alan Bird of Moorfields Eye Hospital in London said that he "would not be surprised to find divers whose damage has progressed far enough to affect their vision". Evidence has mounted during recent years to show that exposure to pressure during diving subtly damages the central nervous system. Doctors believe that the damage is due to obstruction in the flow of blood through the tissues. People who take up diving as a sport know they are at risk of getting "the bends" or an air embolism, but if they follow the correct procedures, the risk is very low. All professional divers know they also run the risk of bone necrosis. About 5 per cent of them develop small dead patches in their bones. Active professional divers have their thighs and upper arms X-rayed as part of their annual medical examination. Doctors have been concerned diving-caused dead patches to appear on bones; other tissues may be suffering a similar fate. Their concern increased in the early 1950s. Detailed neurological examinations and tests of the memory and reactions of experienced professional divers suggested that some of them might have slight damage to the brain and spinal cord. In order to determine the size of the problem, the researchers needed a method of looking for the damage in a large sample of divers that did not involve surgery. The damage which occurs in the tissue of both the bones and the nerves of divers is similar. Damages of the retina which doctors can see using the technique are known as retinal angiography. The process involves injecting fluorocein dye into the blood stream and photographing the back of the eye through the pupil. The technique can provide a detailed photograph of the two vascular systems supplying blood to their retina without causing too much discomfort to the patient. The researchers suggested three mechanisms to explain how diving causes this obstruction. When divers come back to the surface, air bubbles sometimes form in their lungs. Bubbles forming in the lungs trigger changes in the body's clotting mechanism which could result in minute clots. The researchers hope that clues to the cause of the obstruction will come from investigations into the individual differences between divers. Some of the divers studied had relatively little damage even though they had been diving for many years and done a great deal of deep diving. On the other hand, a few inexperienced divers had quite extensive damage.