考研英语阅读资料思维导图

One of the simplest and best known kinds of crystal is the ionic salt, of which a typical example is sodium chloride, or ordinary table salt. The fundamental components of an ionic salt are ions: atoms or molecules that have become electrically charged by gaining or losing one more electrons. In forming sodium chloride, for example, sodium atoms give up an electron (thereby becoming positively charged) and chlorine atoms gain an electron (thereby becoming negatively charged). The ions are attracted to one another by their opposite charges, and they stack together compactly, like tightly packed spheres.

Recently, scientists at Michigan State University created a new kind of crystal called an electride. In electrides, the anions (negative ions) are completely replaced by electrons, which are trapped in naturally formed cavities within a framework of regularly stacked cations (positive ions). Electrides are the first examples of ionic salts in which all these anionic sites are occupied solely by electrons.

Unlike other types of anions, anionic electrons do not behave as if they were simple charged spheres. In particular, because of their low mass and their tendency to interact with one another over great distances, they cannot be "pinned down" to any one location. Instead, they wander close to and among the atoms lining the cavity and interact with electrons in nearby cavities, perhaps changing places with them.

The properties of an electride depend largely on the distance between the cavities that hold trapped electrons. When the trapped electrons are far apart, they do not interact strongly, and so behave somewhat like an array of isolated negative charges. When they are closer together, they begin to display properties associated with large ensembles of identical particles. When they are still closer, the ensemble properties dominate and the electrons "delocalize": they are no longer tightly bound within individual cavities but are more or less free to pass through the spaces within the framework of positive ions.

By synthesizing electrides from a variety of materials, one can vary the geometry of the anionic cavities and their relation to the surrounding cations. The resulting properties may make it possible for electrides to become a basis for economically useful new materials and devices. For instance, because the electrons in some electrides are very weakly bound, these crystals could be effective as photosensitive detectors, in which an impinging photon liberates an electron, resulting in a small electric current. The same weak binding could also make electrides useful in solar energy converters and as cathodes in batteries. One obstacle is the tendency of electrides to decompose through reaction with air and water. Researchers are seeking ways to increase their stability.

1. The text is primarily concerned with discussing

2. In the first paragraph, the author is primarily concerned with

3. According to the text, the defining characteristic of an electride is which of the following?

4. It can be inferred from the text that anions behaving as "simple charged spheres" (line 2, paragraph 3) could be expected to

5. With which of the following statements regarding electrides would the author most likely agree?

Science has long had an uneasy relationship with other aspects of culture. Think of Gallileo's17th-century trial for his rebelling belief before the Catholic Church of poet William Blake's harsh remarks against the mechanistic worldview of Isaac Newton. The schism between science and the humanities has，if anything，deepened in this century.

Until recently，the scientific community was so powerful that it could afford to ignore its critics but no longer. As funding for science has declined，scientists have attacked "antiscience" in several books，notably Higher Superstition，by Paul R.Gross，a biologist at the University of Virginia，and Norman Levitt，a mathematician at Rutgers University; and The Demon-Haunted World，by Car Sagan of Cornell University.

Defenders of science have also voiced their concerns at meetings such as "The Flight from Science and Reason，"held in New York City in1995，and "Science in the Age of(Mis)information，"which assembled last June near Buffalo.

Antiscience clearly means different things to different people. Gross and Levitt find fault primarily with sociologists，philosophers and other academics who have questioned science's objectivity. Sagan is more concerned with those who believe in ghosts，creationism and other phenomena that contradict the scientific worldview.

A survey of news stories in1996reveals that the antiscience tag has been attached to many other groups as well，from authorities who advocated the elimination of the last remaining stocks of smallpox virus to Republicans who advocated decreased funding for basic research.

Few would dispute that the term applies to the Unabomber，whose manifesto，published in1995，scorns science and longs for return to a pretechnological utopia. But surely that does not mean environmentalists concerned about uncontrolled industrial growth are antiscience，as an essay in US News & World Report last May seemed to suggest.

The environmentalists，inevitably，respond to such critics. The true enemies of science，argues Paul Ehrlich of Stanford University，a pioneer of environmental studies，are those who question the evidence supporting global warming，the depletion of the ozone layer and other consequences of industrial growth. Indeed，some observers fear that the antiscience epithet is in danger of becoming meaningless. "The term 'antiscience' can lump together too many，quite different things，"notes Harvard University philosopher Gerald Holton in his1993work Science and Anti-Science. "They have in common only one thing that they tend to annoy or threaten those who regard themselves as more enlightened."

法律类

GOING BACK AND GETTING IT RIGHT

By almost every measure, Paul Pfingst is an unsentimental prosecutor. Last week the San Diego County district attorney said he fully intends to try suspect Charles Andrew Williams, 15, as an adult for the Santana High School shootings. Even before the tragedy, Pfingst had stood behind the controversial California law that mandates treating murder suspects as young as 14 as adults.

So nobody would have wagered that Pfingst would also be the first D.A. in the U.S. to launch his very own Innocence Project. Yet last June, Pfingst told his attorneys to go back over old murder and rape convictions and see if any unravel with newly developed DNA-testing tools. In other words, he wanted to revisit past victories--this time playing for the other team. "I think people misunderstand being conservative for being biased," says Pfingst. "I consider myself a pragmatic guy, and I have no interest in putting innocent people in jail."

Around the U.S., flabbergasted defense attorneys and their jailed clients cheered his move. Among prosecutors, however, there was an awkward pause. After all, each DNA test costs as much as $5,000. Then there's the unspoken risk: if dozens of innocents turn up, the D.A. will have indicted his shop.

But nine months later, no budgets have been busted or prosecutors ousted. Only the rare case merits review. Pfingst's team considers convictions before 1993, when the city started routine DNA testing. They discard cases if the defendant has been released. Of the 560 remaining files, they have re-examined 200, looking for cases with biological evidence and defendants who still claim innocence.

They have identified three so far. The most compelling involves a man serving 12 years for molesting a girl who was playing in his apartment. But others were there at the time. Police found a small drop of saliva on the victim's shirt--too small a sample to test in 1991. Today that spot could free a man. Test results are due any day. Inspired by San Diego, 10 other counties in the U.S. are starting DNA audits.

By Amanda Ripley ez ncisco sijevic rtwell; Lisa McLaughlin; Joseph Pierro; Josh Tyrangiel and Sora Song

注(1)本文选自Time; 03/19/2001, Vol. 157 Issue 11, p62, 1p, 2c, 3bw

注(2)本文习题命题模仿对象2004年真题text 1.

1.How did Pfingst carry out his own Innocence Project?

2.Which of the following can be an advantage of Innocence Project?

3.The expression "flabbergasted"(Line 1, Paragraph 3) most probably means _______.

4.Why was Pfingst an unsentimental prosecutor?

5.Which of the following is not true according to the text?

1.Even before the tragedy, Pfingst had stood behind the controversial California law that mandates treating murder suspects as young as 14 as adults.

1.答案为C，属事实细节题。文中对应信息"Pfingst told his attorneys to go back over old murder and rape convictions and see if any unravel with newly developed DNA-testing tools."是对第二段第一句的补充说明。

2.答案为A，属推理判断题。从上下文我们可以得知，实施"清白计划"就是使用先进的DNA技术来重新审理过去的案件当中可能存在的冤案错案。

3.答案为D, 属猜词题。从第二段第一句话我们得知芬斯特可能是美国第一个实施非常独特的"清白计划"的人，因此他的做法很可能是令人感到吃惊的，从而可猜出该词的含义。

4.答案为B，属推理判断题。从第一段和第二段给出的事例我们可以看出，芬斯特不愿放过任何一个犯罪的人，即便他的年龄还不算大;他也不愿使无辜者蒙冤，即便案件已经审理。

5.答案为C，属推理判断题。正因为 "Pfingst’s move works well",美国才又有"ten other counties are starting DNA audits",而且，"no budgets have been busted or prosecutors ousted".

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