四六级考试

【单选题】

A、DelicateBalance
In 1965 theAmerican statesmanAdlaiE、Stevenson said, "We all travel together, passengers on a little spaceship, 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 affected 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 in 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 ignorance 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 mineral-rich silt on its fertile flood plain before it reached the seA、"Why not dam the river," said the country’s 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 fairy tale is known as the billion- dollarAswan HighDam ofEgypt, and not allEgyptians are living happily ever after.
"For one thing, as water backed up behind the dam, almost 100,000Egyptians had to choose between giving up their family homes and being submerged along with ancient and priceless temples that were part ofEgypt’s 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 farmers who make, on the average, less than a hundred dollars a year each. Furthermore, now there is nothing to wash away the previous year’s 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 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 around 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 even 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 so accelerated the spread of blood flukes that half theEgyptian 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 Goose
Another clear example of human ignorance of nature’s delicate balance is seen in the near extinction of the Hawaiian Goose or Nene. It was estimated in the late eighteenth century that the p
网考网参考答案：C
网考网解析：
[题眼寻踪] Nobody can live around the new lake because______. [原文定位] 在Aswan and Other Fables标题下第三段第二句：So nobody can live around the lake because nobody knows for sure where the shoreline will be． [答案详解] 原文意思为：没人能住在湖边，是因为根本没有人能确定湖岸的边线。与C项“nobody knows for sure where the shoreline will be”相符，故选之。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>