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题库 / Prep2012-CR-20
Public health official: Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who live especially near the lines. However, this is extremely unlikely: Beyond a distance of a few feet, the strength of the magnetic fields from high-voltage power lines is less than the average strength of magnetic fields in homes that are not located near such lines.
Which of the following would it be most useful to establish in order to evaluate the public health argument?
Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes
What proportion of people who live near high-voltage power fines believe that those fines may cause health problems
Whether high-voltage power lines are routed near residential in urban areas
What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines
What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines
感觉a是错的，超过一定距离的高压线磁场既然比home磁场弱，应该讨论的是更弱的的那个有没有危害，讨论更强的有什么意义啊？就好比说，天气热会使企鹅灭绝，南非比南极热，结论是南极会有企鹅，但是如果问以下哪个因素能评估企鹅生存，肯定不是讨论南非的温度是否能让企鹅生存以此来得到南极能让企鹅生存的
是不够严谨，但只能选择最佳答案
本题是评估，不是加强。A项问的是房间内的磁场强度是否对人有伤害，如果没有伤害，那么肯定没问题。如果有伤害，需要进一步评估。所以很完美啊！
人们会在家里长时间停留，但是并不会在高压电线附近长时间待着，（待的时间越长，危害就越大）如果家里的较高强度的磁场对人们都没有危害的话，那么较低强度的，并且人们不常待的磁场影响就更小了。如果有影响的话，那么就需要另做评估了。
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