题目内容
数据结构分为线性数据结构和非线性数据结构，带链的队列属于______。
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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.
某公司下设甲、乙两个投资中心。甲投资中心的投资额为200万元，投资利润率为12%。乙投资中心的投资利润率为16%，剩余收益为18万元：该公司要求的最低投资利润率为10%。该公司决定追加投资200万元。若投向甲投资中心，每年可增加利润26万元；若投向乙投资中心，每年可增加利润34万元。 要求： 若向甲投资中心追加投资，计算追加投资后甲投资中心的剩余收益和投资利润率；
S1. You do not remain at this deep fourth stage all night long, but instead about 80 minutes after you fall into slumber, your brain activity level will increase again slightly.
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. How much of Antarctica is covered by ice
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