单选题They demand to set up an organization flexible enough to cope with any emergency. A. portable B. valiant C. trivial D. mobile

单选题Passage 3 The biosphere is the name biologists give to the sort of skin on the surface of this planet that is inhabitable by living organisms. Most land creatures occupy only the interface between the atmosphere and the land; birds extend their range for a few hundred feet into the atmosphere; burrowing invertebrates (无脊椎动物) such as earthworms may reach a few yards into the soil but rarely penetrate farther unless, it has been recently disturbed by men. Fish cover a wider range, from just beneath the surface of the sea to those depths of greater than a mile inhabited by specialized creatures. Fungi (真菌) and bacteria are plentiful in the atmosphere to a height of about half a mile, blown there by winds from the lower air. Balloon exploration of the stratosphere (同温 层) as long ago as 1936 indicated that moulds and bacteria could be found at heights of several miles, recently the USA's National Aeronautics and Space Administration has detected them, in decreasing numbers, at heights up to eighteen miles. They are pretty sparse at such levels, about one for every two thousand cubic feet, compared with 50 to 100 per cubic foot at two to six miles (the usual altitude of jet aircraft), and they are almost certainly in an inactive state. Marine bacteria have been detected at the bottom of the deep Pacific trench, sometimes as deep as seven miles; they are certainly not inactive. Living microbes have also been obtained on land from cores of rock drilled (while prospecting for oil) at depths of as much as 1,200 feet. Thus we can say, disregarding the exploits of astronauts, that the biosphere has a maximum thickness of about twenty-five miles. Active living processes occur only within a compass of about seven miles, in the sea, on land and in the lower atmosphere, but the majority of living creatures live within a zone of a hundred feet or so. If this planet were sealed down to the size of an orange, the biosphere, at its extreme width, would occupy the thickness of the orange-colored skin, excluding the pith. In this tiny zone of our planet takes place the multitude of chemical and biological activities that we call life. The way in which living creatures interact with each other, depend on each other or compete with each other, has fascinated thinkers since the beginning of recorded history. Living things exist in a fine balance which is often taken for granted, from a practical point of view, things could not be otherwise. Yet it is a source of continual amazement to scientists because of its intricacy and delicacy. The balance of nature is obvious most often when it is disturbed. Yet even here it can seem remarkable how quickly it readjusts itself to a new balance after a disturbance. The science of ecology--the study of the interaction of organisms with their environment--has grown up to deal with the minutiae of the balance of nature.

单选题Many teachers believe that the responsibilities for learning lie with the student.【51】a long reading assignment is given, instructors expect students to be familiar with the【52】in the reading even if they do not discuss it in class or take an examination. The【53】student is considered to be【54】who is motivated to learn for the sake of【55】, not the one interested only in getting high grades. Sometimes homework is returned【56】brief written comments but without a grade. Even if a grade is not given, the student is【57】for learning the material assigned. When research is【58】, the professor expects the student to take it actively and to complete it with【59】guidance. It is the【60】responsibility to find books, magazines, and articles in the library. Professors do not have the time to explain【61】a university library works; they expect students, 【62】graduate students, to be able to exhaust the reference【63】in the library. Professors will help students who need it, but【64】that their students not be【65】dependent on them. In the United States, professors have many other duties【66】teaching, such as administrative or research work.【67】the time that a professor can spend with a student outside class is【68】If a student has problems with classroom work, the student should either【69】a professor during office hours【70】make an appointment.

单选题______your request for an additional assistant, I can only say at this stage that this is being considered.

单选题Which of the following operations may be dangerous?

单选题Having liberated the player from an exclusively team performance, Louis Armstrong Uunwittingly/U codified the vocabulary of the soloist in a series of famous recordings.

单选题A. terrible B. aspect C. respect D. mathematics

单选题I applied for the job that I saw advertised ______ the paper. A. on B. of C. in D. at

单选题After failing his mid-term exams, Jeremy was ______ face his parents.

单选题A very important world problem is the increasing number of people who actually inhabit this planet. The limited amount of land and land resources will soon be unable to support the huge population if it continues to grow at its present rate. So why is this huge increase in population taking place? It is really due to the spread of the knowledge and practice of what is becoming known as "Death Control". You have no doubt heard of the term "Birth Control". "Death Control" is something rather different. It recognizes the work of the doctors and scientists who now keep alive people who, not very long ago, would have died of a variety of then incurable diseases. Through a wide variety of technological innovations that include farming methods and the control of deadly diseases, we have found ways to reduce the rate at which we die. However, this success is the very cause of the greatest threat to mankind. If we examine the amount of land available for this ever-increasing population, we begin to see the problem. If everyone on the planet had an equal share of land, we would each have about 50, 000 square meters. This figure seems to be quite encouraging until we examine the amount of usable land we actually have. More than three-fifths of the world's land cannot produce food. Obviously, with so little land to support us, we should be taking great care not to reduce it further. But we are not! Instead, we are consuming its "capital" — its nonrenewable fossil fuels and other mineral deposits that took millions of years to form but which are now being destroyed in decades. We are also doing the same with other vital resources not usually thought of as being nonrenewable such as fertile soils, groundwater and the millions of other species that share the earth with us. It is a very common belief that the problems of the population explosion are caused mainly by poor people living in poor countries who do not know enough to limit their reproduction. This is not true. The actual number of people in an area is not as important as the effect they have on nature. Developing countries do have an effect on their environment, but it is the populations of richer countries that have a far greater impact on the earth as a whole.

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单选题Whatever happened to the death of newspaper? A year ago the end seemed near. The recession threatened to remove the advertising and readers that had not already fled to the internet. Newspapers like the San Francisco Chronicle were chronicling their own doom. America's Federal Trade commission launched a round of talks about how to save newspapers. Should they become charitable corporations? Should the state subsidize them? It will hold another meeting soon. But the discussions now seem out of date. In much of the world there is the sign of crisis. German and Brazilian papers have shrugged off the recession. Even American newspapers, which inhabit the most troubled come of the global industry, have not only survived but often returned to profit. Not the 20% profit margins that were routine a few years ago, but profit all the same. It has not been much fun. Many papers stayed afloat by pushing journalists overboard. The American Society of News Editors reckons that 13,500 newsroom jobs have gone since 2007. Readers are paying more for slimmer products. Some papers even had the nerve to refuse delivery to distant suburbs. Yet these desperate measures have proved the right ones and, sadly for many journalists, they can be pushed further. Newspapers are becoming more balanced businesses, with a healthier mix of revenues from readers and advertisers. American papers have long been highly unusual in their reliance on ads. Fully 87% of their revenues came from advertising in 2008, according to the Organization for Economic Cooperation ＆ Development (OECD). In Japan the proportion is 35%. Not surprisingly, Japanese newspapers are much more stable. The whirlwind that swept through newsrooms harmed everybody, but much of the damage has been concentrated in areas where newspaper are least distinctive. Car and film reviewers have gone. So have science and general business reporters. Foreign bureaus have been savagely cut off. Newspapers are less complete as a result. But completeness is no longer a virtue in the newspaper business.

单选题Never _______ anything more important before. A. there is B. has there been C. there had D. there has been

单选题Earth is the only (21) we know of in the universe that can support human life. (22) human activities are making the planet less fit to live on. As the western world (23) on consuming two-thirds of the world's resources while half of the world's population do so (24) to stay alive we are rapidly destroying the (25) resource we have by which all people can survive and prosper. Everywhere fertile soil is (26) built on or washed into the sea. Renewable resources are exploited so much that they will never be able to recover (27) . We discharge pollutants (28) the atmosphere without any thought of the consequences. As a (29) the planet's ability to support people is being (30) at the very time when rising human numbers and consumption are (31) increasingly heavy demands on it. The Earth's (32) resources are there for us to use. We need food, water, air, energy, medicines, warmth, shelter and minerals to (33) us fed, comfortable, healthy and active. If we are sensible in how we use the resources they will (34) indefinitely. But if we use them wastefully and excessively they will soon run (35) and everyone will suffer.

单选题Any business needs insurance ______ ordinary risks such as fire, flood and breakage. A. in B. against C. on D. of

单选题Theunderlinedsentenceinthe2ndparagraphdoesNOTmeanthat

单选题Arsenic, a naturally occurring poison and carcinogen found in ground water, is strongly linked to adult-onset diabetes, U. S. researchers said on Tuesday. Odorless, tasteless, colorless and easily soluble in water or wine, arsenic has long been a feared poison. A heavy dose is detectable in a corpse, but researchers say small amounts of arsenic may sicken people gradually. Dr. Ana Navas-Aeien and colleagues at Johns Hopkins University in Baltimore found a " relatively strong " association between commonly found levels of arsenic in urine and type 2 diabetes in a study of American adults. " It seems there is maybe no safe level of arsenic. " Navas-Acien said in a telephone interview. " Worldwide it's a huge problem, " she said. " As water becomes a scarce resource. the situation becomes even more serious. " Arsenic raises the risk for cancers of the bladder, lung, kidney, skin and, possibly, the pros tate, Navas-Acien said. The 20 percent of nearly 800 study participants who had the most arsenic in their bodies, a tolerable 16. 5 micrograms per liter of urine, had 3. 6 times the risk of developing late-onset diabetes than those in the bottom 20 percent, who had 3 micrograms per liter. Levels of arsenic were 26 percent higher in people with late-onset, or type 2, diabetes than those without the disease, the study found. The U. S. government sets a limit for drinking water at 10 micrograms of arsenic per liter, which is exceeded in the water consumed by 13 million Americans who mostly live in rural areas that rely on wells to bring up ground water, the researchers wrote in the Journal of the American Medical Association. Arsenic contaminates drinking water for millions of people in Bangladesh, parts of Central Europe, Chile, Argentina and the western United States, where ground water is the source of drinking water and the land has higher concentrations of arsenic. Overall, 7. 8 percent of Americans are believed to have diabetes, although some do not know it. At least 90 percent of cases are the type 2 variety, in which the body loses its ability to use insulin properly. Navas-Acien said arsenic may play a significant role in diabetes incidence, but it is difficult to say how much. Arsenic can accumulate in the body, and can ruin the body's ability to use insulin and perform the vital task of converting blood sugar into energy. Normally, insulin fits into cells via molecular doorways called receptors, which in turn signal the cell to move glucose inside, but arsenic enters the cell and somehow blocks the activity. Seafood is another source of arsenic, but the organic form found in shellfish and some fish has a carbon molecule attached and poses no risk to health, she said.

单选题Never before ( ) so highly successful in changing his surroundings.

单选题Why do you insist on ________?

单选题When it comes to health, which is more important, nature or nurture? You may well think your genes are a more important predictor of health and ill health. Not so fast. In fact, it transpires that our everyday environment outweighs our genetics, big time, when it comes to measuring our risk of disease. The genome is out—welcome the exposome. "The exposome represents everything a person is exposed to in the environment, that's not in the genes, " says Stephen Rappaport, environmental health scientist at the University of California, Berkeley. That includes stress, diet, lifestyle choices, recreational and medicinal drug use and infections, to name a few. "The big difference is that the exposome changes throughout life as our bodies, diets and lifestyles change, " he says. While our understanding of the human genome has been growing at an exponential rate over the last decade, it is not as helpful as we hoped in predicting diseases. "Genes only contribute 10 percent to the overall disease burden, " says Rappaport. "Knowing genetic risk factors can prove absolutely futile , " says Jeremy Nicholson at Imperial College London. He points to work by Nina Paynter at the Brigham and Women's Hospital in Boston, who investigated the effect of 101 genetic markers implicated in heart disease. After following over 19, 000 women for 12 years, she found these markers were not able to predict anything about the incidence of heart disease in this group. On the other hand, the impact of environmental influences is still largely a mystery. " There's an imbalance between our ability to investigate the genome and the environment, " says Chris Wild, director of the International Agency for Research on Cancer, who came up with the idea of the exposome. In reality, most diseases are probably caused by a combination of the two, which is where the exposome comes in. "The idea is to have a comprehensive analysis of a person's full exposure history, " says Wild. He hopes a better understanding of exposures will shed a brighter light on disease risk factors. There are likely to be critical periods of exposure in development. For example, the time from birth to 3 years of age is thought to be particularly important. "We know that this is the time when brain connections are made, and that if you are obese by this age, you'll have problems as an adult, " says Nicholson.