Questions
16-20 Can electricity cause cancer In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields, which are generated by everything electrical, from power lines and antennas to personal computers and micro-wave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate or the worst kind of paranoia. Now the alarmists have gained some qualified support from the U. S. Enviro A. the force of the electromagnetic field is too weak to be harmful B. the force of the electromagnetic field is weaker than the electric field that the cells generate C. electromagnetic field may affect health D. only more powerful radiation can knock electron out of human body [单项选择]
{{B}}TEXT D{{/B}} Can electricity cause cancer In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields, which are generated by everything electrical, from power lines and antennas to personal computers and micro-wave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate—or the worst kind of paranoia. Now the alarmists have gained some qualified support from the U. S. Environmental Protection Agency. In the executive summary of a new scientific review, released in draft form A. there is casual link between electricity and cancer B. electricity really affects cancer C. controversial D. low frequency electromagnetic field is a possible cause of cancer [单项选择]
A few milliamps of electricity can cause plants to increase synthesis of chemicals. These compounds often also have a pharmacological (related to medicine) or commercial value, so the trick could be used to help increase yields of commercially useful biologicals. Artemisinic acid, from sweet wormwood, for example, is used in malarial medications, and shikonin (紫草素), from the purple gromwell plant, is used against skin infections. 我来回答: 提交
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