Which of the following most logically completes the passage? Using new detection techniques, researchers have found trace amounts of various medicinal substances in lakes and rivers. Taken in large quantities, these substances could have serious health effects, but they are present in quantities far too low to cause any physiological response in people who drink the water or bathe in it. Nevertheless, medical experts contend that eliminating these trace amounts from the water will have public health benefits, since A__E________. A. some of the medicinal substances found in lakes and rivers are harmless to humans even if taken in large quantities B. some of the medicinal substances found in lakes and rivers can counteract possible harmful effects of other such substances found there C. people who develop undesirable side effects when being treated with medicines that contain these substances generally have their treatment changed D. most medicinal substances that reach lakes or rivers rapidly break down into harmless substances E. disease-causing bacteria exposed to low concentrations of certain medicinal substances can become resistant 有抵抗力的to them
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Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade. However, the threshold 门槛;开始of economic viability 生存能力;发育能力for solar power (that is, the price per barrel桶 to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars. Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?c A. The cost of oil has fallen dramatically. B. The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment. C. Technological changes have increased the efficiency of oil-fired power plants. D. Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants. E. When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.
Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation再生;改造;开垦 of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect. Which of the following, if true, most helps to account for the drop in reclamation costs described?BC A. Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country. B. In the twenty years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous twenty years. C. Mine operators have generally ceased终止;结束 surface mining in the mountainous areas of Balzania because reclamation costs per ton of coal produced are particularly high for mines in such areas. D. Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines. E. As compared to twenty years ago, a greater percentage of the coal mined in Balzania today comes from surface mines. 看了好几遍没弄清逻辑关系,生词都查出来了,希望大家帮帮里一下思路o(∩_∩)o...作者: BLinging 时间: 2010-6-7 09:55
95题看懂了,也费了不少时间,是这样的思路: