ElectricBackpack

　　Backpacks are convenient. They can hold your books，your lunch，and achange of clothes，leaving your hands free to do other things.Someday，if youdon't mind carrying a heavy load，your backpacks might also power your MP31player，keep your cell phone running，and maybe even light your wayhome.

　　Lawrence C. Rome and his colleagues from the University of Pennsylvania in Philadelphia2 and the Marine Biological Laboratory in WoodsHole3，Mass.4，have invented a backpack that makes electricity from energyproduced while its wearer walks. In military actions，search-and-rescueoperations，and scientific field studies，people rely increasingly on cellphones，global positioning system (GPS) 5 receivers，night-vision goggles，andother battery powered devices to get around and do their work. The backpack’selectricity- generating feature could dramatically reduce the amount of awearer’s load now devoted to spare batteries，report Rome and his colleagues inthe Sept.9 Science6.

　　The backpack’s electricity-creating powers depend onsprings used to hang a cloth pack from its metal frame.The frame sits againstthe wearer’s back，and the whole pack moves up and down as the person walks.Agear mechanism converts vertical movements of the pack to rotary motions of anelectrical generator，producing up to 7.4 watts.

　　Unexpectedly，tests showedthat wearers of the new backpack alter their gaits in response to the pack’soscillations，so that they carry loads more comfortably and with less effortthan they do ordinary backpacks. Because of that surprising advantage，Rome plans to commercialize both electric and non-electric versionsof the backpack.

　　The backpack could be especially useful forsoldiers，scientists，mountaineers，and emergency workers who typically carryheavy backpacks.For the rest of us，power-generating backpacks could make itpossible to walk，play video games，watch TV，and listen to music，all at the sametime.Electricity-generating packs aren’t on the market yet，but if you do get one eventually，just make sure to look both ways before crossing thestreet!

　　詞匯:

　　backpack/5bAkpAk/n.背包 watt/wCt /n.瓦(特)

　　receiver/ri5si:vE(r)/n.接收機(jī) gait/eit/n.步態(tài)，步法

　　night-visiongoggle 夜視鏡 oscillation/7Csi5leiFEn/n.擺動(dòng)

　　spring/spriN /n.彈簧 commercialize/kE5mE:FElaiz/v.商業(yè)化

　　vertical/5vE:tikEl /adj.垂直的 mountaineer/7maunti5niE(r)/n.登山運(yùn)動(dòng)員

　　rotary/5rEutEri /adj.旋轉(zhuǎn)的

　　練習(xí)：

　　1. Backpacks are convenient because

　　A they can be verylarge.

　　B they can hold as many things as you want to carry.

　　C your handsare freed to do other things.

　　D you do not have to carry things withyou.

　　2. What is the most important feature of the backpack invented byLawrence C.Rome

　　and his colleagues?

　　A It produces electricity forelectronic devices while the wearer walks.

　　B It can be used as cellphones，GPS in the military actions or field studies.

　　C It is small andconvenient.

　　D It is light and easy to carry.

　　3. The word "springs" inParagraph 3 means

　　A a small stream of water flowing naturally from theearth.

　　B the season of the year，occurring between winter and summer.

　　C the act or an instance of jumping or leaping.

　　D a length of metal woundaround，which returns to its original shape after

　　being pushed.

　　4. According to Paragraph 4，what does Rome plan to do?

　　A To make the backpackmore comfortable for the wearer.

　　B To put the backpack on the market.

　　C To test the advantage of the backpack.

　　D To promote the backpack in anewspaper or on television.

　　5. What is implied in “if you do get oneeventually，just make sure to took both

　　ways before crossing the street!”?

　　A You will be too excited to watch the traffic.

　　B Enjoyingelectronic devices while walking may invite traffic accidents.

　　C It is notpossible for you to get such a backpack.

　　D It is wise of you to have such abackpack.

　　答案與題解：

　　1.C第一段告訴我們，因?yàn)楸嘲梢匝b許多東西，所以可以將雙手解放出來(lái)做其他事情：tofree your hands to do other things。

　　2.A第二段的第一句說(shuō)，Lawrence C.Rome及其同事們發(fā)明的這種背包，當(dāng)背著背包走路時(shí)，會(huì)有電能產(chǎn)生;該段最后一句告訴我們，背包的這種性能可減少背包的重量，因?yàn)椴槐財(cái)y帶備用電池。

　　3.D “springs"在此是彈簧的意思。spring是一個(gè)多義詞：泉水(A)、春天(B)、彈跳(C)。

　　4.B 第四段最后一句的意思是：Rome計(jì)劃將這種背包商業(yè)化，即推向市場(chǎng)。A、C、D在文中均未提到。D的意思是為背包做廣告。

　　5.B這個(gè)句子的字面意思是：如果你終于得到這樣的背包，過(guò)馬路時(shí)一定要兩面都看看。也就是說(shuō)，不要因?yàn)橥瑫r(shí)玩著游戲，聽著音樂(lè)、看著電視，太專注以致不注意來(lái)往車輛了。

　　Flying the Hypert1 Skies

　　A little airplane has given new meaning to the term “going hyper.”

　　The Hyper-X2 recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound.That’s about 5,000 miles per hour.At this speed，you’d get around the world ― flying along the equator ― in less than 5 hours.

　　The Hyper-X is an unmanned，experimental aircraft just 12 feet long. It achieves hypersonic speed using a special sort of engine known as a scramjet3.It may sound like something from a comic book，but engineers have been experimenting with scramjets since the 1960s.

　　For an engine to burn fuel and produce energy，it needs oxygen.A jet engine，like those on passenger airplanes，gets oxygen from the air.A rocket engine typically goes faster but has to carry its own supply of oxygen.A scramjet engine goes as fast as a rocket，but it doesn’t have to carry its own oxygen supply.A scramjet's special design allows it to obtain oxygen from the air that flows through the engine.And it does so without letting the fast-moving air put out the combustion flames. However，a scramjet engine works properly only at speeds greater than five times the speed of sound.A booster rocket carried the Hyper-X to an altitude of about 100,000 feet for its test flight.The aircraft’s record-beating flight lasted just 11 seconds.Although the little plane’s self-powered flight lasted only 11 seconds，that brief journey on March 27 makes a major milestone on the way to a new breed of very fast airplanes，comments Werner J.A.Dahm of the University of Michigan in Ann Arbor4.In the future，engineers predict，airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Such hypersonic jets could potentially carry passengers anywhere in the world in just a few hours.

　　Out of the three experimental Hyper-X aircrafts built for NASA5，only one is now left.The agency has plans for another 11-second hypersonic flight，this time at 10 times the speed of the sound.

　　詞匯

　　hypersonic/7haipE(:)5sCnik/adj.超音速的　　 booster/ 5bu:stE/n.助推器

　　equator/i5kweitE(r)/ n.赤道　　　　　　　　　milestone/5mailstEun/n.里程碑

　　unmanned/Qn5mAnd/adj.無(wú)人的 booster rocket 助推火箭

　　scramjet/5skrAmdVet/n.超音速燃燒沖壓式， cargo/5kB:^Eu/n.貨物

　　噴氣發(fā)動(dòng)機(jī)

　　combustion/kEm5bQstFEn/n.燃燒 brink/briNk/n.邊緣

　　練習(xí)：

　　1. The Hyper-X broke the record because

　　A it was the first air-breathing jet plane.

　　B it flew along the equator.

　　C it flew at speeds smaller than five times the speed of sound.

　　D it traveled at a supersonic speed.

　　2. What kind of an engine did the Hyper-X use?

　　A A jet engine that gets oxygen from the air.

　　B A scramjet engine that doesn’t carry its own oxygen supply.

　　C A rocket engine that carries its own supply of oxygen.

　　D A iet engine that uses no oxygen.

　　3. What is NOT true about the scramjet engine?

　　A It goes slower than a rocket.

　　B It extracts oxygen from the air that flows through the engine.

　　C It works only at speeds greater than five times the speed of sound.

　　D It doesn’t carry its own oxygen supply.

　　4. What did Werner J.A.Dahm of the University of Michigan say about the Hyper-X test flight?

　　A It indicated the birth of a very fast airplane.

　　B It was self-powered，so it lasted only 11 seconds.

　　C It can transportcargo quickly and cheaply to the brink of space.

　　D It is a major milestone in the journey of making a new type of very fast airplanes,

　　5. What has NASA planned to do?

　　A To make another 11-second hypersonic flight at 10 times the speed of the sound.

　　B To make three more Hyper-X experiments.

　　C To retest the aircraft that is left.

　　D To make the aircraft fly higher and longer.

　　答案與題解：

　　1. C Hyper-X之所以打破紀(jì)錄是因?yàn)樗娘w行速度是音速的7倍。它不是第一架空氣噴氣式飛機(jī)，也不是第一架超音速飛機(jī)，所以A和D都不對(duì)。Hyper-X的試飛并未繞赤道飛行，所以B也是錯(cuò)誤的選擇。

　　2. B 第四段講了三種發(fā)動(dòng)機(jī)的氧氣來(lái)源：噴氣式發(fā)動(dòng)機(jī)是從空氣中汲取氧氣，火箭發(fā)動(dòng)機(jī)必須自攜氧氣，而超音速?zèng)_壓噴氣發(fā)動(dòng)機(jī)則不必白攜氧氣，而這正是Hyper-X使用的發(fā)動(dòng)機(jī)裝置。

　　3. A 根據(jù)第五段內(nèi)容，B、C、D都是正確的說(shuō)法。第四段最后一句告訴我們，A的說(shuō)法是不正確的。

　　4. D 文章的第六段中，密歇根大學(xué)的研究人員Werner J.A.Dahm說(shuō)，Hyper-X的試飛成功只是研制一種新式快速飛機(jī)過(guò)程中的一個(gè)里程碑(a major milestone on the way to a new breed of very fast airplanes)，而不是新型飛機(jī)的誕生。所以，D是正確選擇，A是錯(cuò)誤選擇。B也不是Werner J.A.Dahm想要表達(dá)的意思。C是其他下程師而不是Werner J.A.Dahm說(shuō)的話。

　　5. A 答案可在最后一段找到。

　　Sugar Power for Cell Phones

　　Using enzymes commonly found in living cells，a new type of fuel cell produces small amounts of electricity from sugar.If the technology is able to succeed in mass production，you may some day share your sweet drinks with your cell phone.

　　In fuel cells，chemical reactions generate electrical currents.The process usually relies on precious metals，such as platinum.In living cells，enzymes perform a similar job，breaking down sugars to obtain electrons and produce energy.

　　When researchers previously used enzymes in fuel cells，they had trouble keeping them active，says Shelley D.Minteer of St Louis University1.Whereas biological cells continually produce fresh enzymes，there’s no mechanism in fuel cells to replace enzymes as they quickly degrade.

　　Minteer and Tamara Klotzbach，also of St Louis University，have now developed polymers that wrap around an enzyme and preserve it in a microscopic pocket.“We tailor these pockets to provide the ideal microenvironment” for the enzyme，Minteer says.The polymers keep the enzyme active for months instead of days.

　　In the new fuel Cell，tiny polymer bags of enzyme are embedded in a membrane that coats one of the electrodes.When glucose from a sugary liquid gets into a pocket，the enzyme oxidizes it，releasing electrons and protons.The electrons cross the membrane and enter a wire through which they travel to the other electrode，where they react with.oxygen in the atmosphere to produce water.The flow of electrons through the wire constitutes an electrical current that can generate power.

　　So far，the new fuel cells don’t produce much power，but the fact that they work at all is exciting，says Paul Kenis，a chemical engineer at the University of Illinois2 at Urhana-Champaign3.“Just getting it to work.” Kenis says，“is a major accomplishment.”

　　Sugar-eating fuel cells could be an efficient way to make electricity.Sugar is easy to find. And the new fuel cells that run on it are biodegradable，so the technology wouldn’t hurt the environment.The scientists are now trying to use different enzymes that will get more power from sugar.They predict that popular products may be using the new technology in as little as 3 years.

　　詞匯：

　　enzyme/5enzaIm/n.酶 electrode/I5lektrEJd/n.電極platinum/5plAtinEm/n.鉑，白金 membrane/5membrein/n.膜，薄膜

　　electron/I5lektrRn/n.電子 oxidize/5Cksi7daiz/v.氧化degrade/di5reid/v.降解 glucose/5lu:kEus/n.葡萄糖

　　polymer/5pClimE/n.聚合物 biodegradable/7baiEudi5reidEbl/adj.能進(jìn)行生物降解的

　　microenvironment n.微環(huán)境 embed/im5bed/v.埋置，插入

　　proton/5prEutCn/n.質(zhì)子

　　試題

　　1. According to the first paragraph，when can we share our sweet drinks with our cell phones?

　　A When enzymes can be commonly found in living ceils.

　　B When the technology of producing a new type of fuel cell appears.

　　C When the technology of a new type of fuel cell is suitable for mass production.

　　D When the technology of mass producing cell phones appears.

　　2. What trouble did Minteer and Klotzhach have in their research?

　　A They had trouble keeping enzymes in fuel cells active.

　　B They had trouble keeping biological cells active.

　　C They had trouble producing fresh enzymes.

　　D They had trouble finding mechanism for producing enzymes.

　　3. According to Paragraph 5，electrons are released

　　A when bags of enzyme are embedded in the new fuel cell.

　　B when glucose from a sugary liquid goes through the enzyme.

　　C when the enzyme oxidizes the glucose from a sugary liquid that goes through

　　a pocket.

　　D when the enzyme oxidizes the sugary liquid that goes through a pocket.

　　4. What is exciting about the new fuel cells?

　　A Their limitless power generation capacity is amazing.

　　B Their limited power generation capacity is a good beginning.

　　C Their limited power generation capacity is the result of great efforts.

　　D Their limitless power generation capacity is a major accomplishment,

　　5. According to the last paragraph，what is NOT true of the new fuel cells?

　　A The new fuel cells run on sugar that is easy to find.

　　B The new fuel cells are environment friendly.

　　C The new fuel cells are biologically degradable,

　　D It will take some time before the new fuel cells can be used in popular products.

　　答案與題解：

　　1. C A和D明顯不是正確答案。B不是正確選擇，因?yàn)橹挥挟?dāng)這種新的燃料電池被大規(guī)模生產(chǎn)時(shí)，才有可能實(shí)現(xiàn)用甜飲料給手機(jī)提供電能。

　　2. A 文章第三段的第一句是問(wèn)題的答案。

　　3. C 該段第二句“When glucose from a sugary liquid penetrates a pocket，the enzyme oxidizes it，releasing electrons and proton”中的it指代glucose，而不是a sugary liquid，因 此C是正確選擇。

　　4. B 第六段的大意是，盡管這種新型燃料電池還不能產(chǎn)牛很多電能，但是，它能夠產(chǎn)生電能的事實(shí)就已經(jīng)是很大的成就了。因而激動(dòng)人心。所以只有B是正確答案。

　　5. D 文章的最后一段指出了這種新型燃料電池的優(yōu)點(diǎn)，即A、B、C所述內(nèi)容。最后一句說(shuō)，科學(xué)家預(yù)計(jì)，在不到三年的時(shí)間里這種新技術(shù)便可在大眾的流行產(chǎn)品中使用。所以D是正確選擇。

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