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考研綜合演練與答案詳解（1）
Passage 1
Environment pollution is a worldwide concern. Some scientists believe that there are four major pollutions surrounding us——water pollution, atmosphere pollution, noise pollution and electromagnetic pollution. And some even think electricity can cause cancer. Can electricity really cause cancer? In a society that literally runs on electric power, the very idea seems preposterous. 1) __________________________________________________. 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.
2) __________________________________________________. 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 (ELF) ——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.”
3)____________________________________________________.
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. 4) __________________________________________________. The ELF magnetic field generated by a video terminal measures only a few milligauss, or about one-hundredth the strength of the earth's own 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.
5) __________________________________________________. Though there is a body of laboratory work showing that exposure to ELF field can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found.
[A] Now the alarmists have gained some qualified support from the U. S. Environmental Protection Agency ( EPA ).
[B] 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.
[C] However, there are still some people insist that even low-frequency electromagnetic fields is extremely harmful to human's health.
[D] But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect.
[E] The report is no reason to panic - or even to lest sleep, ff 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 Bush Administration, and the EPA released it over strong objections from the Pentagon and the Whit House. But now no one can deny that the issue must be taken seriously and that much more research is needed.
[F] Consequently, the epidemiological studies, taken as a whole, consist of a few early low-quality studies, some of which yielded positive effects, and later, higher-quality studies, which yielded negative studies. If power lines really caused cancer, it is natural to expect the later studies to confirm the earlier studies. Instead, this has all the earmarks of a nonexistent effect.
[G] For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak.
【文章大意及結(jié)構(gòu)分析】
這是一篇關(guān)于電磁波是否致癌的科普文章。電能導致癌癥嗎?在一個依靠電力運行的社會里，這個觀點似乎荒唐�？墒窃絹碓蕉嗟目茖W家和新聞工作者指出，接觸電磁場有增加白血病和其他惡性疾病危險的可能性。但這種可能性還沒有定論。美國環(huán)境保護署發(fā)布報告指出，甚低頻的電磁場和白血病，淋巴瘤和腦癌之間有“—種偶然的聯(lián)系”。我們沒有理由為此恐慌，即使有患癌癥的危險，這種風險也是很小的。尚且對它的證據(jù)還有很大的爭議。爭議的焦點是一個簡單的物理現(xiàn)象：當電流通過電線時，會產(chǎn)生一個對周圍物體施加壓力的電磁場。這個壓力極其微弱。比細胞自身產(chǎn)生的電場壓力還低得多。如此小的力量不會對健康構(gòu)成威脅。最近，科學家研究強大輻射離子。離子化的輻射毫無疑問會增加患癌癥的風險�？墒牵ㄟ^流行病學研究，也不能證明它們之間的因果關(guān)系。
本文共分6個自然段。作者采用“提出問題——分析原因——解決問題”這一行文格式。第一段作者提出問題：電流能導致癌癥嗎? 第二段到第五段中對這一問題進行分析。第二段說環(huán)境保護機構(gòu)報告：電磁場和某些癌癥之間有“偶然的聯(lián)系”；第三段講，對這一結(jié)論的證據(jù)爭論很大。第四段講，電磁場的壓力很小，對人體無害；第五段又提出，離子化輻射增加患癌癥的風險。第六段是結(jié)論，根據(jù)所做的流行病學研究，沒有發(fā)現(xiàn)它們之間的因果關(guān)系，而且試驗室對動物的實驗，也沒有發(fā)現(xiàn)電流致癌的生理機制。
【解題思路與答案詳解】
1) 【答案】[B]。本題在第一段的中間。根據(jù)它的上下文來推斷它的內(nèi)容。它前面講，電流能導致癌癥嗎?在一個基本上依靠電力來運行的社會里，這個觀點似乎有點荒唐（Can electricity really cause cancer? In a society that literally runs on electric power, the very idea seems preposterous.）。它后面講，這種可能性還沒有定論（The implications are unsettling）。其中The implications就是解題的線索，本題的內(nèi)容應(yīng)該講“這種可能性”。據(jù)此，我們可以確定選項[B]是正確答案。其意為：十幾年來，越來越多的科學家和新聞工作者指出，接觸電磁場有增加患白血病和其他惡性疾病風險的可能性。
2) 【答案】[A]。本題在第二段的開始。前一段講到，越來越多的科學家和新聞工作者認為接觸電磁場有增加患白血病和其他惡性疾病的風險，但沒有得到證實。本段其余部分主要講，美國環(huán)境保護署發(fā)出了最為嚴肅的政府警告。甚低頻的電磁場和白血病，淋巴瘤和腦癌之間有“—種偶然的聯(lián)系” （the EPA has put forward what amounts to the most serious government warning, …“suggests a casual link” between extremely low-frequency electromagnetic fields (ELF)…and leukemia, lymphoma and brain cancer）。據(jù)此推斷，本題應(yīng)該是一個過渡句或過渡句組，起承上啟下的作用，連接這兩個段落。另外其中the EPA也是一個解題的線索。所以選項[A]是正確答案。句意為：現(xiàn)在，“杞人憂天者”已經(jīng)獲得了來自美國環(huán)境保護署的正式的支持。
3) 【答案】[E]。 本題是一個獨立的自然段，即文章的第三段。獨立的段落有兩種可能，一是過渡段，一是擴展段；這要根據(jù)它的前后段落的內(nèi)容來判斷。它前一段主要講，EPA報告電流有某種致癌的危險；它后一段講，爭議的焦點是一個簡單的，很好理解的物理現(xiàn)象（At the heart of the debate is a simple and well-understood physical phenomenon）等。據(jù)此可以推斷，本段講到關(guān)于這一問題的爭論。所以，選項[E]是正確答案。這是一個典型的過渡段落。其意為：報告說沒有理由恐慌——甚至失眠。即使有患癌癥的危險，這種風險也是很小的。證據(jù)的爭議性仍然很大，草案激起了布什政府內(nèi)部很多爭論。環(huán)境保護署是克服了五角大樓和白宮的強烈反對而發(fā)布此報告的。不過現(xiàn)在沒有人否認有必要進行更多的研究并認真對待這個問題。
4) 【答案】[G] 。本題在第四段的中間。可以根據(jù)它的上下文來選擇答案。它前面講的是，爭論的焦點是個簡單的物理現(xiàn)象——當電流通過電線時，會產(chǎn)生一個對周圍物體施加壓力的電磁場（…when an electric current passes through a wire, it generates an electromagnetic field that exerts forces on surr
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