大学四级-1294及答案解析.doc
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1、大学四级-1294 及答案解析(总分:713.00,做题时间:90 分钟)一、Part Writing(总题数:1,分数:106.00)1.1. 眼下大学生在外租房居住的现象十分普遍2. 对比分析在外租房居住和住在学校宿舍的利弊3. 我的看法(分数:106.00)_二、Part Reading Compr(总题数:1,分数:70.00)A Delicate BalanceIn 1965 the American statesman Adlai E Stevenson said, “We all travel together, passengers on a little spaceship,
2、 dependent on its vulnerable supplies of air and soil. We manage to survive by the care, work, and love we give our fragile craft.“ Our planet is indeed fragile. Every living thing on this planet is part of a complicated web of life, for no organism lives entirely on its own. Every organism is affec
3、ted by all that surrounds it whether living or nonliving. And in turn each organism has some effect on its surroundings.Even the most elementary understanding of ecology requires knowledge of this cause/effect relationship all organisms have on each other. Every thing we do to our environment will i
4、n one way or another affect the quality of life we experience on this tiny spaceship. If we want the quality of life to be high, we must be more aware that nature is a finely balanced mechanism and that it will not tolerate the abuse we have been giving it. Consider the following examples of human i
5、gnorance concerning the delicate balance of nature.Aswan and Other Fables“Once there was a country that desperately needed food and energy for its growing population. It happened that one of the most magnificent rivers in the world flowed through this country. Each year the river deposited tons of m
6、ineral-rich silt on its fertile flood plain before it reached the sea. “Why not dam the river,“ said the countrys leaders, “and use the water to irrigate more land, control the annual spring flooding of the river, and provide hydroelectric power all at the same time?“ The result of this modern-day f
7、airy tale is known as the billion- dollar Aswan High Dam of Egypt, and not all Egyptians are living happily ever after.“For one thing, as water backed up behind the dam, almost 100,000 Egyptians had to choose between giving up their family homes and being submerged along with ancient and priceless t
8、emples that were part of Egypts cultural heritage. But there have been far more devastating results. Now that the Nile River floodplain is deprived of its annual enrichment with silt, artificial fertilizer has to be trucked in at a cost of 100 million dollars a year a cost carried by the subsistence
9、 farmers who make, on the average, less than a hundred dollars a year each. Furthermore, now there is nothing to wash away the previous years silt buildup in the soil. And with silt deposits no longer compensating for erosion, the fertile river delta is shrinking and an alarming part of what remains
10、 has completely dried up. Restoring the delta with pumps, drains, and wells may cost more than the dam itself.“Ironically, evaporation as well as bottom seepage from the new lake filling in behind the dam is so great that the lake basin may never fill up to predicted levels. So nobody can live aroun
11、d the lake because nobody knows for sure where the shoreline will be. More seriously, there is less water to go around than there was before. And even though some 700,000 new acres (about 1.6 million hectares) have been opened up for agriculture, the population outgrew the potential food increase ev
12、en before the dam was finished. At the same time, with the nutrient-rich flow of the Nile turned off, another major food source-the sardines, shrimp, and mackerel that flourished in the enriched waters off the delta has declined catastrophically. Worse yet, the lake and the irrigation networks have
13、so accelerated the spread of blood flukes that half the Egyptian populace are now carriers of schistosomiasis (血吸虫病). In irrigated areas, where eight out of ten humans live, women can expect to live only to age twenty-seven, men to age twenty-five.“The Hawaiian GooseAnother clear example of human ig
14、norance of natures delicate balance is seen in the near extinction of the Hawaiian Goose or Nene. It was estimated in the late eighteenth century that the population of Hawaiis unique variety of goose stood at about 25,000. In a matter of fifty years the population had dropped to approximately thirt
15、y birds. There were undoubtedly multiple causes for the decline in the Nene population, and virtually all of them resulted, either directly or indirectly, from humans.The most disastrous activities of humans included hunting with firearms, ranching activities, and the building of beach resorts. Ther
16、e is little doubt that the Nenes near extinction was hastened after shotguns were brought to Hawaii. It seems reasonable to assume that many more Nenes were killed when guns became common. In a similar fashion, as people moved further inland on the islands they began to open more and more land for t
17、he development of ranches and beach resorts. These developments forced the geese out of their natural nesting and breeding ranges. As these ranches and resorts became more plentiful, the Nene population accordingly decreased.The most harmful indirect effect of humans activities was the introduction
18、of animals such as cattle, goats, mongooses, and game birds. When cattle were first brought to the islands, King Kamehameha proclaimed a ten-year protection of the animals. They were allowed to roam the islands unrestrained. They multiplied rapidly, and as they did they moved further and further int
19、o the virgin forests, destroying many of the plants that provided food and shelter for the Nene. The goats that were introduced to the islands were even more destructive to the Nene natural habitat. Because the goats were more agile, not only could they reach the plants at the lower elevations, but
20、they also moved into the high-lands. In 1882, the mongoose was introduced to Hawaii in hopes that it would control the rats that were doing great damage in the sugar cane fields. The mongoose neither solved the rat problem nor remained in the sugar cane fields. As it moved out of the cane fields, it
21、 did what it does naturally: it became a predator of ground-nesting birds-including the Nene. The game birds introduced to Hawaii (quail, turkey, and guinea hen) all encroached on the Nenes already severely limited natural range. With the limited land space that an island has, the Nene had no escape
22、 route and no time to build defenses against these rapidly arriving unnatural opponents.By the 1940s, the Nene population had dwindled to a number so low that almost nothing could be done to save this unique, tame, land-living goose. It had become a classic example of our unconscious destruction of
23、nature.Mosquito PlagueStill another famous incident drives home the intricate relationships within our ecosystem. Some years ago, large quantities of DDT were used by the World Health Organization in a program of mosquito control in Borneo. Soon the local people, spared a mosquito plague, began to s
24、uffer a plague of caterpillars, which devoured the thatched roofs of their houses, causing them to fall in. The habits of the caterpillars limited their exposure to DDT, but predatory wasps that had formerly controlled the caterpillars were devastated.Further spraying was done indoors to get rid of
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- 大学 1294 答案 解析 DOC
