教师资格初中英语学科知识与教学能力第二章英语教学知识（中）材料题根据以下材料，回答45-49题（江南博哥）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 legitimateor 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 late last week,the EPA has put forward what amounts to the most serious government warning to date. The agency tentatively concludes that scientific evidence“suggests a casual link” between extremely low-frequency electromagnetic fields-those having very long wave-lengths-and leukemia,lymphoma and brain cancer, while the report falls short of classifying ELF fields as probable carcinogens, it does identify the common 60-hertz magnetic field as “a possible, but not proven, cause of cancer in humans”.The report is no reason to panic-or even to lost sleep. If there is a cancer risk, it is a small one. The evidence is still so controversial that the draft stirred a great deal of debate within the Administration, and the EPA released it over strong objections from the Pentagon and the White House. But now no one can deny that the issue must be taken seriously and that much more research is needed.At the heart of the debate is a simple and well-understood physical phenomenon: When an electric current passes through a wire, it generates an electromagnetic field that exerts forces on surrounding objects. For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak. The ELF magnetic field generated by a video terminal measures only a few milligauss, or about one-hundredth the strength of the earthsown magnetic field, the electric fields surrounding a power line can be as high as 10 kilovolts per meter, but the corresponding field induced in human cells will be only about 1 millivolt per meter.This is far less than the electric fields that the cells themselves generate.How could such minuscule forces pose a health danger? The consensus used to be that they could not, and for decades, scientists concentrated on more powerful kinds of radiation, like X-rays, that pack sufficient wallop to knock electrons out of the molecules that make up the human body. Such “ionizing” radiations have been clearly linked to increased cancer risks and there are regulations to control emissions.But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect. Though there is a body of laboratory work showing that exposure to ELF fields can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found.The Pentagon is far from persuaded. In a blistering 33-page critique of the EPA report, Air Force scientists charge its authors with having “biased the entire document”toward proving a link.“Our reviewers are convinced that there is no suggestion that(electromagnetic fields) present in the environment induce or promote cancer,”the Air Force concludes. “It is astonishing that the EPA would lend its imprimatur on this report.” Then Pentagons concern is understandable.There is hardly a unit of the modern military that does not depend on the heavy use of some kind of electronic equipment, from huge ground-based radar towers to the defense systems built into every warship and plane.45 单选题 The main idea of this passage is_. 查看材料A.studies on the cause of cancerB.controversial viewpoints in the cause of cancerC. the relationship between electricity and cancerD.different ideas about the effect of electricity on cancer正确答案：D 参考解析：主旨题。全文主要围绕人们关于电流对癌症影响的不同观点展开叙述，分别介绍了科学家、美国环保署、美国国防部等的观点。故本题选D。46 单选题 The view point of the EPA is_. 查看材料A.there is casual link between electricity and cancerB.electricity really affects cancerC. controversialD. low frequency electromagnetic field is a possible cause of cancer正确答案：A 参考解析：细节题。根据关键词定位至原文第二段。根据“The agency tentatively concludes that scientific evidencesuggests a casual linkbetween extremely low-frequency electromagnetic fields-those having very long wavelengthsand leukemia，lymphoma and brain cancer”可知，美国环保署认为电流与癌症之间有着某种难以确定的关系。故本题选A。47 单选题 Why did the Pentagon and White House obje