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 t
A. countering a flawed argument that dismisses a possible solution to problem
B. reconciling contradictory points of view about the nature of a problem
C. identifying the strengths of possible solutions to a problem
D. discussing a problem and arguing in favor of one solution to it
As we have seen in earlier chapters,
the American definition of success is largely one of acquiring wealth and a
higher material standard of living. It is not surprising, therefore, that
Americans have valued education for its monetary value. The belief is widely
spread in the United States that the more schooling people have, the more money
they will earn when they leave school. The belief is strongest regarding the
desirability of an undergraduate university degree, or a professional degree
such as medicine or law following the undergraduate degree. The money value of
graduate degrees in "non-professional" fields such as art, history, or
philosophy is not as great. This belief in the monetary value of education is supported by statistics on income. Ben Wattenberg, a social scientist, estimated that in the course of a lifet A. He was proud to have finished high school. B. He became a successful leader thanks to his education. C. He wished he hadn’t dropped out of school. D. He was a liar. 我来回答: 提交
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