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In 1971 there were about 3,700 million people in the world. If the population were (21) evenly over the earth’ s surface there would be about 50 people to the square mile; but there are vast areas of desert and mountain and tropical forest (22) are uninhabited, (23) at the other (24) , in the great cities millions may live within a few square miles. (25) of the world’ s population is concentrated on only a small (26) of the earth’ s land surface, in the rich valleys and (27) plains, because people up to the present time have (28) to congregate in place where the climate and soil make it easy to grow food and obtain shelter. A (29) world population and the discoveries of science (30) this pattern of distribution in the future. As men slowly learn to master diseases, control floods, prevent famines, and stop wars, fewer people die every year; and in (31) the population of the world is steadily (32) . When numbers (33) , the extra mouths must be fed. New lands must be brought (34) cultivation, or land already (35) , made to yield larger crops. In some areas the accessible land is largely so intensively cultivated (36) it will be difficult to make it (37) more food. in some areas the population is so dense that the land is divided into. units (38) tiny to allow for much improvement in farming methods. (39) a large part of this farming population drawn (40) into industrial occupations, the land might be farmed much more productively by modern methods.
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Passage 3 Most scientists blame people, at least in part, for global warming. Now, some researchers say people may be partly to blame for the cooling of Antarctica as well. While average global temperatures have risen about one degree Fahrenheit over the past century, Antarctica over all appears to have cooled slightly in the past few decades. That has been puzzling, because the polar regions are thought to be more sensitive to warming trends than the rest of the globe. Even more puzzling, a small portion of Antarctica--the peninsula that stretches north toward South America--defies the cooling trend. It has been warming very rapidly, about five degrees over the past 50 years, 10 times the global average. Writing in today’ s issue of the journal Science, Dr. David Thompson, a professor of atmospheric science at Colorado State University, and Dr. Susan Solomon, a senior scientist at the National Oceanic and Atmospheric Administration in Boulder, Colo., argue that the ozone hole, which has opened up each spring over Antarctica in recent years, may help explain both contradictory trends. A vortex of winds continually blows around Antarctica, tending to trap cold air at the South Pole. In the new paper, Dr. Thompson and Dr. Solomon show that the winds have strengthened in the past few decades, keeping the cold air even more confined. The peninsula, which lies outside the wind vortex, escapes the cooling effect, the scientists said. They say the ozone hole may be the cause of the stronger winds. Close to the ground, ozone, a molecule consisting of three oxygen atoms, forms a large and unhealthy component of smog. High in the atmosphere, however, nature occurring ozone is essential for life, blocking ultraviolet rays that would fatally mangle DNA. However, fewer ozone molecules mean the atmosphere absorbs less ultraviolet radiation. Instead of warming the air, the rays bounce off the snow and ice of Antarctica and reflect back into space. Scientists already knew that the ozone hole had cooled the upper atmosphere. Dr. Thompson and Dr. Solomon show that the troposphere, the lowest six miles of the atmosphere, has also cooled. "It’ s a lot of food for thought in there," said Dr. John Walsh, a professor of atmospheric science at the University of Illinois and an author of a paper in Science in January that indicated Antarctica was cooling. He noted that the ozone hole was usually largest in November or December, but that the greatest cooling had been about six months later. Which of the following is NOT the reason for the rapid warming of the peninsula mentioned in Para. 2
计算机工作时，内存储器中存储的是______。
In 1971 there were about 3,700 million people in the world. If the population were (21) evenly over the earth’ s surface there would be about 50 people to the square mile; but there are vast areas of desert and mountain and tropical forest (22) are uninhabited, (23) at the other (24) , in the great cities millions may live within a few square miles. (25) of the world’ s population is concentrated on only a small (26) of the earth’ s land surface, in the rich valleys and (27) plains, because people up to the present time have (28) to congregate in place where the climate and soil make it easy to grow food and obtain shelter. A (29) world population and the discoveries of science (30) this pattern of distribution in the future. As men slowly learn to master diseases, control floods, prevent famines, and stop wars, fewer people die every year; and in (31) the population of the world is steadily (32) . When numbers (33) , the extra mouths must be fed. New lands must be brought (34) cultivation, or land already (35) , made to yield larger crops. In some areas the accessible land is largely so intensively cultivated (36) it will be difficult to make it (37) more food. in some areas the population is so dense that the land is divided into. units (38) tiny to allow for much improvement in farming methods. (39) a large part of this farming population drawn (40) into industrial occupations, the land might be farmed much more productively by modern methods.
Passage 4 For many years, Antarctica was thought to be only an archipelago whose islands were tied together above sea level by ice. It was thought to be made up of two small subcontinents--East Antarctica, the larger, and West Antarctica, containing the Antarctic Peninsula. The two continents were supposed to be separated by a large trough, below sea level, that connected the Ross and Weddell Seas. Geophysical studies have now revealed a fairly complete picture of the Antarctic landform below its ice cover. We know now that West Antarctica is connected to the main part of the continent by a chain of mountains well above sea level, though largely buried by ice and snow. The bedrock of much of East Antarctica appears to be above sea level. Whether mineral wealth lies hidden by the vast ice sheets is unknown. No more than 2 percent of the continent is actual rock outcrop and much of this small and probably unrepresentative sample has yet to be visited by geologists. Certainly no deposits rich enough to be economically useful have been found. Geologists now know that the ice-buried rocks of the Antarctic are similar to rocks of the other continents of the world. Minor amounts of potentially valuable minerals have been reported. The presence of petroleum has been speculated upon by several geologists, but none has yet been found. Low-grade deposits of coal are widespread, especially in the Transantarctic Mountains, but there has been no attempt at exploitation. Even if rich mineral deposits were to be found in Antarctica, the cost of removal from this remote and inhospitable land would be exorbitant. Interpretation of continental structure is an important objective of any extensive geologic investigation. Yet except for the earth’ s ocean basins, no area the size of Antarctica is so geologically unknown. With 98 percent of the continent covered by ice, it is extremely difficult to decipher the continent’ s general structure. Geologists determine geologic structure by studying rock outcrops, and many of these are small and widely separated. No outcrops are known in the vast interior of East Antarctica. Working out the continental structure of Antarctica is analogous to learning that of the entire United States from studies of a few scattered counties in California and mountain ranges scattered at irregular intervals across the country. Low-grade deposits of coal have been found in Antarctica’ s ______ .
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