Test C16, In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography. Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989? (A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988. (B) In December of 1988 a new and far more accurate gas spectrometer was invented. (C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful. (D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures. (E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area. 答案为B。我觉得应该是D。主要是从时间上考虑。 B中1998.12月有了一种更准确的spectrometer，说明以前的仪器测出的数据不准确，所以才会有97,98年数据高，而99年数据低的结果。不过这个选项有个缺陷：invented，如果改成“使用”会更好。 D的时间为1988年，亦即可能在年初也可能在年末，如果在年初的话，很可能这些local industries会被勒令立即进行pollution control，从而在1988年当年就减少了alert的天数。所以二者相较，我更倾向于B.
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发表于 2003-12-7 20:07:00
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