考研英語模擬題

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考研英語模擬題

　　在日常學習和工作中，我們需要用到試題的情況非常的多，試題是學�；蚋髦鬓k方考核某種知識才能的標準。什么樣的試題才是好試題呢？以下是小編整理的考研英語模擬題，歡迎大家分享。

考研英語模擬題

　　Section Ⅰ Use of English

　　Direction,hello!

　　Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C or D on ANSWER SHEET 1. (10 points)

　　There is growing interest in East Japan Railway Co. ltd., one of the six companies, created out of the privatized national railway system. In an industry lacking exciting growth__1__, its plan to use real-estate assets in and around train stations__2__is drawing interest.

　　In a plan called "Station Renaissance" that it__3__in November, JR East said that it would__4__using its commercial spaces for shops and restaurants, extending them to__5__more suitable for the information age. It wants train stations as pick-up__6__for such goods as books, flowers and groceries__7__over the Internet. In a country where city__8__depend heavily on trains__9__commuting, about 16 million people a day go to its train stations anyway, the company __10__. So, picking up commodities at train stations__11__consumers extra travel and missed home deliveries. JR East already has been using its station__12__stores for this purpose, but it plans to create__13__spaces for the delivery of Internet goods.

　　The company also plans to introduce __14__cards-known in Japan as IC cards because they use integrated circuit for__15__information__16__ train tickets and commuter passes__17__the magnetic ones used today, integrating them into a/an __18__pass. This will save the company money, because__19__for IC cards are much less expensive than magnetic systems. Increased use of IC cards should also__20__the space needed for ticket vending.

　　1.[A]perspectives [B]outlooks [C]prospects [D]spectacles

　　2.[A]creatively [B]originally [C]authentically [D]initially

　　3.[A]displayed [B]demonstrated [C]embarked [D]unveiled

　　4.[A]go beyond [B]set out [C]come around [D]spread over

　　5.[A]applications [B]enterprises [C]functions [D]performances

　　6.[A]districts [B]vicinities [C]resorts [D]locations

　　7.[A]acquired [B]purchased [C]presided [D]attained

　　8.[A]lodgers [B]tenants [C]dwellers [D]boarders

　　9.[A]for [B]in [C]of [D]as

　　10.[A]figures [B]exhibits [C]convinces [D]speculates

　　11.[A]deprives [B]retrieves [C]spares [D]exempts

　　12.[A]conjunction [B]convenience [C]department [D]ornament

　　13.[A]delegated [B]designated [C]devoted [D]dedicated

　　14.[A]clever [B]smart [C]ingenious [D]intelligent

　　15.[A]checking [B]gathering [C]holding [D]accommodating

　　16.[A]as [B]for [C]with [D]of

　　17.[A]but for [B]as well as [C]instead of [D]more than

　　18.[A]unique [B]single [C]unitary [D]only

　　19.[A]devices [B]instruments [C]readers [D]examiners

　　20.[A]reduce [B]narrow [C]dwarf [D]shrink

　　答案

　　1.C 2.A 3.D 4.A 5.C 6.D 7.B 8.C 9.A 10.A

　　11.C 12.B 13.D 14.B 15.C 16.A 17.C 18.B 19.C 20.A

　　Section Ⅱ Reading Comprehension

　　Part A

　　Directions:

　　Read the following four texts. Answer the questions below each text by choosing A, B, C or D. Mark your answers on ANSWER SHEET 1. (40 points)

　　Text 1

　　"I've never met a human worth cloning," says cloning expert Mark Westhusin from the cramped confines of his lab at Texas A&M University. "It's a stupid endeavor." That's an interesting choice of adjective, coming from a man who has spent millions of dollars trying to clone a 13-year-old dog named Missy. So far, he and his team have not succeeded, though they have cloned two calves and expect to clone a cat soon. They just might succeed in cloning Missy later this year-or perhaps not for another five years. It seems the reproductive system of man's best friend is one of the mysteries of modern science.

　　Westhusin's experience with cloning animals leaves him vexed by all this talk of human cloning. In three years of work on the Missyplicity project, using hundreds upon hundreds of canine eggs, the A&M team has produced only a dozen or so embryos carrying Missy's DNA. None have survived the transfer to a surrogate mother. The wastage of eggs and the many spontaneously aborted fetuses may be acceptable when you're dealing with cats or bulls, he argues, but not with humans. "Cloning is incredibly inefficient, and also dangerous," he says.

　　Even so, dog cloning is a commercial opportunity, with a nice research payoff. Ever since Dolly the sheep was cloned in 1997, Westhusin's phone at A&M College of Veterinary Medicine has been ringing busily. Cost is no obstacle for customers like Missy's mysterious owner, who wishes to remain unknown to protect his privacy. He's plopped down $3.7 million so far to fund the research because he wants a twin to carry on Missy's fine qualities after she dies. But he knows her clone may not have her temperament. In a statement of purpose, Missy's owners and the A&M team say they are "both looking forward to studying the ways that her clone differs from Missy."

　　The fate of the dog samples will depend on Westhusin's work. He knows that even if he gets a dog viably pregnant, the offspring, should they survive, will face the problems shown at birth by other cloned animals: abnormalities like immature lungs and heart and weight problems. "Why would you ever want to clone humans," Westhusin asks, "when we're not even close to getting it worked out in animals yet?"

　　1. Which of the following best represents Mr. Westhusin's attitude toward cloning?

　　[A] Animal cloning is a stupid attempt.

　　[B] Human cloning is not yet close to getting it worked out.

　　[C] Cloning is too inefficient and should be stopped.

　　[D] Animals cloning yes, and human cloning at least not now.

　　2. The Missyplicity project does not seem very successful probably because _____.

　　[A] there isn't enough fund to support the research

　　[B] cloning dogs is more complicated than cloning cats and bulls

　　[C] Mr. Westhusin is too busy taking care of the business

　　[D] the owner is asking for an exact copy of his pet

　　3. When Mr. Westhusin says "... cloning is dangerous," he implies that _____.

　　[A] lab technicians may be affected by chemicals

　　[B] cats and dogs in the lab may die of diseases

　　[C] experiments may waste lots of lives

　　[D] cloned animals could outlive the natural ones

　　4. We can infer from the third paragraph that _____.

　　[A] rich people are more interested in cloning humans than animals

　　[B] cloning of animal pets is becoming a prosperous industry

　　[C] there is no distinction between a cloned and a natural dog

　　[D] Missy's master pays a lot in a hope to revive the dog

　　5. We may conclude from the text that _____.

　　[A] human cloning will not succeed unless the technique is more efficient

　　[B] scientists are optimistic about cloning technique

　　[C] many people are against the idea of human cloning

　　[D] cloned animals are more favored by owners even if they are weaker

　　答案

　　1. D 2.B 3.C 4.B 5.A

　　Text 2

　　For more than two decades, U.S. courts have been limiting affirmative-action programs in universities and other areas. The legal rationale is that racial preferences are unconstitutional, even those intended to compensate for racism or intolerance. For many colleges, this means students can be admitted only on merit, not on their race or ethnicity. It has been a divisive issue across the U.S., as educators blame the prolonged reaction to affirmative-action for declines in minority admissions. Meanwhile, activists continue to battle race preferences in courts from Michigan to North Carolina.

　　Now, chief executives of about two dozen companies have decided to plunge headfirst into this politically unsettled debate. They, together with 36 universities and 7 nonprofitable organizations, formed a forum that set forth an action plan essentially designed to help colleges circumvent court-imposed restrictions on affirmative action. The CEOs' motive: "Our audience is growing more diverse, so the communities we serve benefit if our employees are racially and ethnically diverse as well", says one CEO of a compang that owns nine television stations.

　　Among the steps the forum is pushing: finding creative yet legal ways to boost minority enrollment through new admissions policies; promoting admissions decisions that look at more than test scores; and encouraging universities to step up their minority outreach and financial aid. And to counter accusations by critics to challenge these tactics in court, the group says it will give legal assistance to colleges sued for trying them. "Diversity diminished by the court must be made up for in other legitimate, legal ways," says, a forum member.

　　One of the more controversial methods advocated is the so-called 10% rule. The idea is for public universities-which educate three-quarters of all U.S. undergraduates-to admit students who are in the top 10% of their high school graduating class. Doing so allows colleges to take minorities who excel in average urban schools, even if they wouldn't have made the cut under the current statewide ranking many universities use.

　　1. U.S. court restrictions on affirmative action signifies that______.

　　[A]minorities no longer hold the once favored status

　　[B]the quality of American colleges has improved

　　[C]racial preferences has replaced racial prejudice

　　[D]the minority is on an equal footing with the majority

　　2. What has been a divisive issue across the United States?

　　[A]Whether affirmative action should continue to exist.

　　[B]Whether this law is helping minorities or the white majority.

　　[C]Whether racism exists in American college admission.

　　[D]Whether racial intolerance should be punished.

　　3. CEOs of big companies decided to help colleges enroll more minority students because they_____.

　　[A]think it wrong to deprive the minorities of their rights to receive education

　　[B]want to conserve the fine characteristics of American nation

　　[C]want a workforce that reflects the diversity of their customers

　　[D]think it their duty to help develop education of the country

　　4. The major tactic the forum uses is to_____.

　　[A]battle the racial preferences in court

　　[B]support colleges involved in lawsuits of racism

　　[C]strive to settle this political debate nationwide

　　[D]find legally viable ways to ensure minority admissions

　　5. If the 10% rule is applied, ______.

　　[A]the best white high school students can get into colleges

　　[B]public universities can get excellent students

　　[C]students from poor rural families can go to colleges

　　[D]good minority students can get into public universities

　　答案

　　1. A 2.B 3.C 4.D 5.D

　　Text 3

　　Positive surprises from government reports on retail sales, industrial production, and housing in the past few months are leading economists to revise their real gross domestic product (GDP) forecasts upward supporting the notion that the recession ended in December or January.

　　Bear in mind: This recovery won't have the vitality normally associated with an upturn.

　　Economists now expect real GDP growth of about 1.5 in the first quarter. That's better than the 0.4 the consensus projected in December, but much of the additional growth will come from a slower pace of inventory drawdowns, not from surging demand.

　　Moreover, the economy won't grow fast enough to help the labor markets much. The only good news there is that jobless claims have fallen back from their spike after September 11 and that their current level suggests the pace of layoffs is easing.

　　The recovery also does not mean the Federal Reserve will raise interest rates soon. The January price indexes show that inflation remains tame. Consequently, the Fed can take its time shifting monetary policy from extreme accommodation to relative neutrality.

　　Perhaps the best news from the latest economic reports was the January data on industrial production. Total output fell only 0.1, its best showing since July. Factory output was flat, also the best performance in six months. Those numbers may not sound encouraging, but manufacturers have been in recession since late 2000. The data suggest that the factory sector is finding a bottom from which to start its recovery.

　　Production of consumer goods, for instance, is almost back up to where it was a year ago. That's because consumer demand for motor vehicles and other goods and the housing industry remained healthy during the recession, and they are still growing in early 2002.

　　Besides, both the monthly homebuilding starts number and the housing market index for the past two months are running above the averages for all of 2001, suggesting that home-building is off to a good start and probably won't be big drag on GDP growth this year.

　　Equally important to the outlook is how the solid housing market will help demand for home-related goods and services. Traditionally, consumers buy the bulk of their furniture, electronics, and textiles within a year of purchasing their homes. Thus, spending on such items will do well this year, even as car sales slip now that incentives are less attractive. Look for the output of consumer goods to top year-ago level in coming months.

　　Even the business equipment sector seems to have bottomed out. Its output rose 0.4% in January, led by a 0.6% jump computer gear. A pickup in orders for capital goods in the fourth quarter suggests that production will keep increasing-although at a relaxed pace-in coming months.

　　1. American economists are surprised to see that______.

　　[A]they have to revise the GDP forecasts so often

　　[B]their government is announcing the end of a recession

　　[C]US economy is showing some signs of an upturn

　　[D]GDP growth reflects stronger domestic demand

　　2. The most encouraging fact about the US economy is that_____ .

　　[A]employment rates have risen faster than expected

　　[B]the Federal Reserve will raise interest rates soon

　　[C]industrial production is reaching its lowest point

　　[D]some economic sectors have become leading industries

　　3. Of which of the following did the author provide a guardedly optimistic view?

　　[A]GDP growth. [B]The number of layoffs.

　　[C]Price indexes. [D]Output of consumer goods.

　　4. Which of the following is the guarantee of a better future for US economy?

　　[A]Motor vehicles. [B]Housing market.

　　[C]Business equipment. [D]Computer gear.

　　5. Which of the following best summarizes the U. S. economic situation today?

　　[A]American economists are painting a gloomy picture.

　　[B]It is slowly warming up with moderate growth.

　　[C]Recession may come back anytime in the coming months.

　　[D]Most sectors are picking up at a surprisingly fast pace.

　　答案

　　1.C 2.C 3.A 4.B 5.B

　　Text 4

　　Timothy Berners-Lee might be giving Bill Gates a run for the money, but he passed up his shot at fabulous wealth-intentionally-in 1990. That's when he decided not to patent the technology used to create the most important software innovation in the final decade of the 20th century: the World Wide Web. Berners-Lee wanted to make the world a richer place, not a mass personal wealth. So he gave his brainchild to us all.

　　Berners-Lee regards today's Web as a rebellious adolescent that can never fulfill his original expectations. By 2005, he hopes to begin replacing it with the Semantic Web-a smart network that will finally understand human languages and make computers virtually as easy to work with as other humans.

　　As envisioned by Berners-Lee, the new Web would understand not only the meaning of words and concepts but also the logical relationships among them. That has awesome potential. Most knowledge is built on two pillars: semantics and mathematics. In number-crunching, computers already outclass people. Machines that are equally adroit at dealing with language and reason won't just help people uncover new insights; they could blaze new trails on their own.

　　Even with a fairly crude version of this future Web, mining online repositories for nuggets of knowledge would no longer force people to wade through screen after screen of extraneous data. Instead, computers would dispatch intelligent agents, or software messengers, to explore Web sites by the thousands and logically sift out just what's relevant. That alone would provide a major boost in productivity at work and at home. But there's far more.

　　Software agents could also take on many routine business chores, such as helping manufacturers find and negotiate with lowest-cost parts suppliers and handling help-desk questions. The Semantic Web would also be a bottomless trove of eureka insights. Most inventions and scientific breakthroughs, including today's Web, spring from novel combinations of existing knowledge. The Semantic Web would make it possible to evaluate more combinations overnight than a person could juggle in a lifetime. Sure scientists and other people can post ideas on the Web today for others to read. But with machines doing the reading and translating technical terms, related ideas from millions of Web pages could be distilled and summarized.

　　That will lift the ability to assess and integrate information to new heights. The Semantic Web, Berners-Lee predicts, will help more people become more intuitive as well as more analytical. It will foster global collaborations among people with diverse cultural perspectives, so we have a better chance of finding the right solutions to the really big issues-like the environment and climate warming.

　　1. Had he liked, Berners-Lee could have _____.

　　[A]created the most important innovation in the 1990s

　　[B]accumulated as much personal wealth as Bill Gates

　　[C]patented the technology of Microsoft software

　　[D]given his brainchild to us all

　　2. The Semantic Web will be superior to today's web in that it _____.

　　[A]surpasses people in processing numbers

　　[B]fulfills user's original expectations

　　[C]deals with language and reason as well as number

　　[D]responds like a rebellious adult

　　3. To search for any information needed on tomorrow's Web, one only has to _____.

　　[A]wade through screen after screen of extraneous data

　　[B]ask the Web to dispatch some messenger to his door

　　[C]use smart software programs called "agents"

　　[D]explore Web sites by the thousands and pick out what's relevant

　　4. Thanks to the Web of the future, _____.

　　[A]millions of web pages can be translated overnight

　　[B]one can find most inventions and breakthroughs online

　　[C]software manufacturers can lower the cost of computer parts

　　[D]scientists using different specialty terms can collaborate much better

　　5. The most appropriate title for this text is.

　　[A]Differences between Two Webs

　　[B]The Humanization of Computer Software

　　[C]A New Solution to World Problems

　　[D]The Creator and His Next Creation

　　答案

　　1. B 2.C 3.C 4.D 5.D

　　Part B

　　Directions:

　　In the following article, some sentences have been removed. For Questions 41-45, choose the most suitable one from the lish A-G to fit into each of the numbered blank. There are two extra choices that do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)

　　The making of weathervanes (devices fixed on the top of buildings to show directions of the wind) is an ancient skill, going back to early Egyptian times. Today the craft is still very much alive in the workshop that Graham Smith has set up. He is one of the few people in the country who make hand-cut weathervanes. Graham's designs are individually created and tailored to the specific requirements of his customers. "That way I can produce a unique personalized item," he explains, "A lot of my customers are women buying presents for their husbands. They want a distinctive gift that represents the man's business or leisure interests."

　　It's all a far cry from the traditional cock, the most common design for weathervanes.

　　It was not a cock but a witch on a broomstick that featured on the first weathervane Graham ever made. Friends admired his surprise present for his wife and began asking him to make vanes for them. "I realized that when it came to subjects that could be made into them, the possibilities were limitless," he says.

　　(41)_____________.

　　That was five years ago and he has no regrets about his new direction. "My previous work didn't have an artistic element to it, whereas this is exciting and creative," he says. "I really enjoy the design side."

　　(42) _____________.

　　Graham also keeps plenty of traditional designs in stock, since they prove as popular as the one-offs. "It seems that people are attracted to handcrafting," Graham says. "They welcome the opportunity to acquire something a little bit different."

　　(43) _____________.

　　"I have found my place in the market. People love the individuality and I get a lot of satisfaction from seeing a nondescript shape turn into something almost lifelike," he says.

　　(44) _____________.

　　"And nowadays, with more and more people moving to the country, individuals want to put an exclusive finishing touch to their properties. It has been a boost to crafts like mines,"

　　(45) _____________.

　　American and Danish buyers in particular are showing interest. "Pricing," he explains, "depends on the intricacy of the design."His most recent request was for a curly-coated dog. Whatever the occasion, Graham can create a gift with a difference.

　　[A]Graham has become increasingly busy, supplying flat-packed weathervanes to clients worldwide.

　　[B]Graham decided to concentrate his efforts on a weathervane business. He had served an apprenticeship as a precision engineer and had worked in that trade for 15 years when he and his wife, Liz, agreed to swap roles-she went out to work as an architectural assistant and he stayed at home to look after the children and build up the business.

　　[C]Last month, a local school was opened with his galleon ship weathervane hoisted above it.

　　[D]"For centuries, weathervanes have kept communities in touch with the elements, signaling those shifts in wind direction that bring about changes in the weather," he explains.

　　[E]Graham has no plans for expansion, as he wants to keep the business as a rural craft.

　　[F]Graham has now perfected over 100 original designs. He works to very fine detail, always seeking approval for the design of the silhouette from the customer before proceeding with the hand-cutting.

　　答案

　　41. B 42.F 43.E 44.D 45.A

　　Part C

　　Directions:

　　Read the following text carefully and then translate the underlined segments into Chinese. Your translation should be written clearly on ANSWER SHEET 2. (10 points)

　　The value which society places on work has traditionally been closely associated with the value of individualism and as a result it has had negative effects on the development of social security. (46) It has meant that in the first place the amount of benefits must be small lest people's willingness to work and support themselves suffers. Even today with flat rate and earnings-related benefits, the total amount of the benefit must always be smaller than the person's wages for fear of malingering. "The purpose of social security," said Huntford referring to Sweden's comparatively generous benefits, "is to dispel need without crossing the threshold of prosperity." Second, social security benefits are granted under conditions designed to reduce the likelihood of even the boldest of spirits attempting to live on the State rather than work. Many of the rules surrounding the payment of unemployment or supplementary benefit are for this purpose. Third, the value placed on work is manifested in a more positive way as in the case of disability. (47) People suffering from accidents incurred at work or from occupational diseases receive preferential treatment by the social security service compared with those suffering from civil accidents and ordinary illnesses.

　　Yet, the stranglehold which work has had on the social security service has been increasingly loosened over the years. The provision of family allowances, family income supplements, the slight liberalization of the wages stop are some of the manifestations of this trend. (48) Similarly, the preferential treatment given to occupational disability by the social security service has been increasingly questioned with the demands for the upgrading of benefits for the other types of disability. It is felt that in contemporary industrial societies the distinction between occupational and non-occupational disability is artificial for many non-occupational forms of disability have an industrial origin even if they do not occur directly in the workplace. (49) There is also the additional reason which we mentioned in the argument for one benefit for all one-parent families, that a modern social security service must concentrate on meeting needs irrespective of the cause behind such needs.

　　The relationship between social security and work is not all a one-way affair. (50) It is true that until very recently the general view was that social security "represented a type of luxury and was essentially anti-economic." It was seen as merely government expenditure for the needy. As we saw, however, redundancy payments and earnings-related unemployment benefits have been used with some success by employers and the government to reduce workers' opposition towards loss of their jobs.

　　46譯文：首先，這種觀念認為，救濟金的數(shù)額必須小，以免損害人們主動工作，自食其力的積極性。

　　47譯文：與那些遭受個人意外和忍受普通疾病折磨的人相比，因公受傷或者患有職業(yè)病的人在社會保障服務方面享有優(yōu)待。

　　48譯文：同樣，社會保障服務給予職業(yè)傷殘的優(yōu)惠待遇越來越多地受到了質(zhì)疑，人們要求提高對其他類型傷殘的救濟。

　　49譯文：此外，還有一個我們在討論單親家庭救濟問題時所提及的理由，即一個現(xiàn)代的社會保障服務必須專注于滿足需求，不管這些需求的背后有何原因。

　　50譯文：誠然，直到最近，普遍的觀點依然認為社會保障"體現(xiàn)的是一種享受，從本質(zhì)上講是反經(jīng)濟的"。它僅僅被看作是政府用于貧困群體的開支。

　　Section Ⅲ Writing

　　Part A

　　51. Directions:

　　You have received an invitation to the birthday party of your friend, Tom. But you can't attend it. Write a note to Tom to

　　1) thank him for the invitation,

　　2) give reasons why you can't go, and

　　3) apologize and express your wishes.

　　You should write about 100 words neatly on ANSWER SHEET 2. Do not sign your own name. Use "Li Ming" instead. You do not need to write the address. (10 points)

　　一、審題與謀篇

　　本題要求寫一封道歉信。寫道歉信一般是因為寫信人不能完成所要求或許諾的事情，或不能按時或很好地完成某件事情。道歉一般和解釋同時存在，解釋是出于禮貌、希望消除可能的誤解。道歉要真誠，解釋要充分并且切題，寫信的語氣要溫和而富于策略。

　　指導語中給出的情景是接到朋友生日會的邀請但不能參加，信的內(nèi)容包括：(1)表示感謝;(2)說明你不能參加生日會的理由;(3)道歉并表達祝愿。

　　二、參考范文

　　Thank you very much for inviting me to your birthday party tomorrow and I have been longing for giving my sincere wishes to you on that special day. However, I am terribly sorry that I cannot be there because of a matter of some urgency. This afternoon I got a call from my parents telling me that my sister had been hospitalized. Both of my parents are busy at work, so I have to go home in a hurry to take care of her. I am sure you can understand this. I would like to say sorry again and wish you a happy birthday as well as a successful party.

　　52. Directions:

　　Look at the flowing picture and write an article on advertisement. Your article should cover the points below:

　　1) The omnipresence (無所不在，普遍)of advertisements

　　2) Their advantages

　　3) Their disadvantages

　　You should write 160-200 words neatly on ANSWER SHEET 2 (20 points)

　　參考范文

　　Advertisements come into our lives in a variety of forms. Newspapers carry advertisements. Billboards carry advertisements. More conspicuously, TV advertisements are incessantly influencing people's life from various aspects.

　　Advertisements have many advantages. Firstly, advertising is informative, which provides us with a quick access to the product needed. Secondly, many advertisements, especially TV advertisemnts are so beautifully made that they themselves can bring us great enjoyment. Maybe that's why the daughter in the picture is so attracted by them.

　　However, advertising involves some defects. Firstly, the cost of adverting will definitely be passed on to the customers, which makes the products be sold at much higher prices. Thirdly, Secondly, The advertisers often mispresent the truth by exaggerating the benefits of the merchandise they want to sell. Thirdly, advertisements often interrupt audiences' appreciation of their favorite programs, which may lead to diasspointment and frustration, the expression written on the face of the father in the picuture,As far as I am concerned, I tend to be in favor of the positive effects. Undoubtedly, nothing is more important than convenience for people living in a so quick-paced society. I believe that the negative effects can be minimized through sustainable economic growth and education.

　　推薦：

　　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

　　[A] a way to isolate electrons.

　　[B] the characteristics of a new kind of crystal.

　　[C] the structure of an ionic salt.

　　[D] commercial uses for electrides.

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

　　[A] introducing a variant on the standard atomic theory.

　　[B] describing how chlorine atoms can become negatively charged.

　　[C] describing some early research at Michigan State University.

　　[D] providing background for the technical discussion to follow.

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

　　[A] Its positive are of particularly low mass.