单选题The geology of the Earth"s surface is dominated by the particular properties of water. Present on Earth in solid, liquid, and gaseous states, water is exceptionally reactive. It dissolves, transports, and precipitates many chemical compounds and is constantly modifying the face of the Earth.
Evaporated from the oceans, water vapor forms clouds, some of which are transported by wind over the continents. Condensation from the clouds provides the essential agent of continental erosion: rain. Precipitated onto the ground, the water trickles down to form brooks, streams, and rivers, constituting what is called the hydrographic network. This immense polarized network channels the water toward a single receptacle: an ocean. Gravity dominates this entire step in the cycle because water tends to minimize its potential energy by running from high altitudes toward the reference point that is sea level.
The rate at which a molecule of water passes through the cycle is not random but is a measure of the relative size of the various reservoirs. If we define residence time as the average time for a water molecule to pass through one of the three reservoirs--atmosphere, continent, and ocean--we see that the times are very different. A water molecule stays, on an average, eleven days in the atmosphere, one hundred years on a continent and forty thousand years in the ocean. This last figure shows the importance of the ocean as the principal reservoir of the hydrosphere but also the rapidity of water transport on the continents.
A vast chemical separation process takes places during the flow of water over the continents. Soluble ions such as calcium, sodium, potassium, and some magnesium are dissolved and transported. Insoluble ions such as aluminum, iron, and silicon stay where they are and form the thin, fertile skin of soil on which vegetation can grow. Sometimes soils are destroyed and transported mechanically during flooding. The erosion of the continents thus results from two closely linked and interdependent processes, chemical erosion and mechanical erosion. Their respective interactions and efficiency depend on different factors.
单选题Forget football. At many high schools, the fiercest competition is between Coke and Pepsi over exclusive "pouring rights" to sell on campus. But last week Jeffrey Dunn, president of Coca-Cola Americas, called a timeout: Coke's machines will now also stock water, juice, and other healthful options--even rival brands and their facades will feature school scenes and other "noncommercial graphics" instead of Coke's vivid red logo. "the pendulum needs to swing back" on school-based marketing, said Dunn. Coke's about-face--particularly the call to end the exclusive deals that bottlers make with school districts--comes amid rising concern over kids' health: American children are growing ever more obese and developing weight-related diseases usually found in adults. While inactivity and huge helpings factor heavily, a recent study in the Lancet fingered soda pop as a likely culprit. Communities--and legislators--are already on the case. Last year, for instance, parents in Philadelphia detailed a proposed contract with Coca-Cola that would have netted the school system $ 43 million over 10 years. And in a searing' report to congress last month, the U. S. Department of Agriculture recommended that all snacks sold in schools meet federal nutrition standards (the requirements are loose enough that Snickers bars qualify). Spare change? Activists hope Coke's capitulation will help curb commercialism in schools altogether. From ads on Channel One, which broadcasts current-affairs programs on classroom TV, to middle-school math texts that cite Nike and other bran-name products in their word problems, to company-sponsored scoreboards on football fields, American pupils are bombarded. But Andrew Hagelshaw, executive director of the Oakland, Calif.-based Center for Commercial-Free Public Education, views Coca-Cola's policy shift as a "partial victory". Schools sign contracts with local bottlers; the parent company can only urge them to back off. Moreover, Coke's machines will remain in place, although with healthier options. And don't expect teenagers to suddenly swear off the stuff--or school districts to give up the revenue. At Wheeler High School in Marietta, Ga., where students arrive before 7 a.m. and stay as late as 11 o'clock at night, they rely on the machines. And the $ 50,000 in annual vending revenues have enabled Principal Joe Boland to refinish the gym floor, in- stall a new high-jump pit, and pay $ 7,000 for two buses. "If someone made an offer to me to take the machines out, I'd consider it," says Boland. "But nobody's offering me any money./
单选题I think it is high time we ______ the fact that environmental pollution in this area is getting more serious than before.
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单选题The policeman tried to ______ the teenage driver to obey the traffic laws rather than fine him directly.
单选题The engineers in this lab spent several weeks______their plans for the new bicycle.
单选题The bank manager asked his assistant if it was possible for him to
______ the investment plan within a week.
A. work out
B. make out
C. put out
D. set out
单选题The manager promised to pay them well and in return he would expect their loyalty and ______.
单选题Death ensued as a result of Usuffocation/U.
单选题 If the gain of profit is solely due to rising energy prices, then inflation should be subsided when energy prices ______.
单选题The mother is told that her child is desperately ill—the chances of survival are slim, and the treatment is as Udreadful/U as the disease.
单选题Why does the Foundation concentrate its support on basic rather than applied research? Basic research is the very heart of science, and its cumulative product is the capital of scientific progress, a capital that must be constantly increased as the demands upon it rise. The goal of basic research is understanding, for its own sake. Understanding of the structure of the atom or the nerve cell, the explosion of a spiral nebula or the distribution of cosmic dust, the causes of earthquakes and droughts, or of man as a behaving creature and of the social forces that are created whenever two or more human beings come into contact with one another--the scope is staggering, but the commitment to truth is the same. If the commitment were to a particular result, conflicting evidence might be overlooked or, with the best will in the world, simply not appreciated. Moreover, the practical applications of basic research frequently cannot be anticipated. When Roentgen, the physicist, discovered X-rays, he had no idea of their usefulness to medicine. Applied research, undertaken to solve specific practical problems, has an immediate attractiveness because the results can be seen and enjoyed. For practical reasons, the sums spent on applied research in any country always far exceed those for basic research, and the proportions are more unequal in the less developed countries. Leaving aside the funds devoted to research by industry--which is naturally far more concerned with applied aspects because these increase profits quickly--the funds the U.S. Government allots to basic research currently amount to about 7 percent of its overall research and development funds. Unless adequate safeguards are provided, applied research invariably tends to drive out basic. Then, as Dr. Waterman has pointed out, "Developments will inevitably be undertaken prematurely, career incentives will gravitate strongly toward applied science, and the opportunities for making major scientific discoveries will be lost. Unfortunately, pressures to emphasize new developments, without corresponding emphasis upon pure science tend to degrade the quality of the nation's technology in the long run, rather than to improve it./
单选题Usually he managed to find plenty of work to ______ him over hard times, I think it is a good idea. A. chew B. blow C. flip D. tide
单选题Assuming that a constant travel-time budget, geographic constraints and short-term infrastructure constraints persist as fundamental features of global mobility, what long-term results can one expect? In high-income regions, (41) North America, our picture suggests that the share of traffic (42) supplied by buses and automobiles will decline as high-speed transport rises sharply. In developing countries, we (43) the strongest increase to be in the shares first for buses and later for automobiles. Globally, these (44) in bus and automobile transport are partially offsetting. In all regions, the share of lowspeed mil transport will probably continue its strongly (45) decline. We expect that throughout the period 1990~2050, the (46) North American will continue to devote most of his or her 1.1-hour travel-time (47) to automobile travel. The very large demand (48) air travel (or high-speed mil travel) that will be manifest in 2050 (49) to only 12 minutes per person a day; a little time goes a long way in the air. In several developing regions, most travel (50) in 2050 will still be devoted to nonmotorized modes. Buses will persist (51) the primary form of motorized transportation in developing countries for decades. (52) important air travel becomes, buses, automobiles and (53) lowspeed trains will surely go on serving vital functions. (54) of the super-rich already commute and shop in aircraft, but average people will continue to spend most of their travel time on the (55) .
单选题Lisa stood motionless at the end of the diving board, hands at her sides, heels slightly raised, every muscle ______ action.
单选题Jazz tends to be a casual dialogue form of dance quite ______ in the receptive and mechanical forms of the waltz. A. lacked B. lacking C. for lack of D. lack of
单选题The Japanese personnel manager had to ______ keeping a chemist on the payroll even though the company no longer needed his expertise.(2011年南京师范大学考博试题)
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Unlike the carefully weighed and
planned compositions of Dante, Goethe's writings have always the sense of
immediacy and enthusiasm. He was a constant experimenter with life, with ideas,
and with forms of writing. For the same reason, his works seldom have the
qualities of finish or formal beauty which distinguish the masterpieces of Dante
and Virgil. He came to love the beauties of classicism, but these were never an
essential part of his makeup. Instead, the urgency of the moment, the spirit of
the thing, guided his pen. As a result, nearly all his works have serious
flaws of structure, of inconsistencies, of excesses and redundancies and
extraneities. In the large sense, Goethe represents the fullest
development of the romanticist. It has been argued that he should not be so
designated because he so clearly matured and outgrew the kind of romanticism
exhibited by Wordsworth, Shelley, and Keats. Shelley and Keats died young;
Wordsworth lived narrowly and abandoned his early attitudes. In contrast, Goethe
lived abundantly anti developed his faith in the spirit, his understanding of
nature and human nature, and his reliance on feelings as man's essential
motivating force. The result was all-encompassing vision of reality and a
philosophy of life broader and deeper than the partial visions and attitudes of
other romanticists. Yet the spirit of youthfulness, the impatience with close
reasoning or "logic-chopping," and the continued faith in nature remained his to
tile end, together with an occasional waywardness and impulsiveness and a
disregard of artistic or logical propriety which savor strongly of romantic
individualism. Since so many twentieth century thoughts and attitudes are
similarly based on the stimulus of the Romantic Movement, Goethe stands as
particularly the poet of the modern man as Dante stood for medieval man and as
Shakespeare for the man of the Renaissance.
单选题Which of the following is the writer implying in paragraph 4?
