Nature constantly adjusts the atmospheric carbon level. An increase in the level causes the atmosphere to hold more heat, which causes more water to evaporate from the oceans, which causes increased rain. Rain washes some carbon from the air into the oceans, where it eventually becomes part of the seabed. A decrease in atmosphere carbon causes decreased evaporation from the oceans, which cause less rain, and thus less carbon is washed into the oceans. Yet some environmentalists worry that burning fossil fuels may raise atmospheric carbon to a dangerous level. It is true that a sustained increase would threaten human life. But the environmentalists should relax---nature will continually adjust the carbon level.
133. Which one of the following, if true, would most weaken the argument in the passage?
A. Plant life cannot survive without atmospheric carbon.
B. It is not clear that breathing excess carbon in the atmosphere will have a negative effect on human life.
C. Carbon is part of the chemical “blanket” that keeps the Earth warm enough to sustain human life.
D. Breathing by animals releases almost 30 times as much carbon as does the burning of fossil fuels.
E. The natural adjustment process, which occurs over millions of years, allow wide fluctuations in the carbon level in the short term.
Answer E
In my view, the reasoning in this argument is that:
nature will continually adjust the carbon levelà a sustained increase in the level of carbon would not threaten human life.
能否帮忙分析得更透彻些。作者: ryanyhu 时间: 2010-1-4 21:26
原文中说：Yet some environmentalists worry that burning fossil fuels may raise atmospheric carbon to a dangerous level.这和E选项中的allow wide fluctuations in the carbon level in the short term是相对应的，所以环境学家worry的事情事实上还是会发生。 文章的结论其实暗含说这种情况不会发生，因此E是削弱结论。作者: girlwithwings 时间: 2010-1-6 04:35
一針見血。
