| Several recent studies have gained wide
attention for reconfirming the tragic disconnection of millions of black youths
from the American mainstream. Harry Holzer, an economist at Georgetown
University and a co-author of one of the recent studies, feels joblessness is
due to largely weak schooling, a lack of reading and math skills at a time when
such skills are increasingly required even for blue-collar jobs. Unable to find
jobs, he claims, black males turn to illegal activities, especially the drug
trade and chronic drug use, and often end up in prison. As usual, it fails to answer the important questions. Why are young black men doing so poorly in school that they lack basic literacy and math skills Scholars must have known that countless studies by educational experts have found that poor schools, per se(本质上), do not explain why after 10 years o A. It enables black youths to get into employment. B. It provides black youths with reading and math skills. C. It prevents black youths from illegal activities. D. It decreases drug trade and drug use among black youth. [单项选择]Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing. Consequently more than 100 cities in the United States still have levels of carbon monoxide, particulate matter, and ozone (generated by photochemical reactions with hydrocarbons from vehicle exhaust) that exceed legally established limits. There is a growing realization that the only effective way to achieve further reductions in vehicle emissions--short of a massive shift away from the private automobile—is to replace conventional diesel fuel and gasoline with cleaner-burning fuels such as compressed natural gas, liquefied petroleum gas, ethanol, or methanol.
All of these alternatives are carbon-based fuels whose molecules are smaller and simpler than those of gasoline. These molecules burn mom cleanly than gasoline, in part because they have fewer, if any, carbon-carbon bonds, and the hydrocarbons they do emit are A. Further attempts to reduce emissions from gasoline-fueled vehicles will nor help lower urban air pollution levels. B. Attempts to reduce the pollutants that an individual gasoline-fueled vehicle emits have been largely unsuccessful. C. Few serious attempts have been made to reduce the amount of pollutants emitted by gasoline fueled vehicles. D. Pollutants emitted by gasoline-fueled vehicles are not the most critical source of urban air pollution. 我来回答: 提交
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