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       ElectricBackpack

　　Backpacksare convenient.They can hold your books,your lunch,and achange ofclothes,leaving your hands free to do other things.Someday,if youdont mindcarrying a heavy load,your backpacks might also power your MP31player,keep yourcell phone running,and maybe even light your wayhome.

　　LawrenceC.Rome and his colleagues from the University of Pennsylvania in Philadelphia2and the Marine Biological Laboratory in WoodsHole3,Mass.4,have invented abackpack that makes electricity from energyproduced while its wearer walks.Inmilitary actions,search-and-rescueoperations,and scientific fieldstudies,people rely increasingly on cellphones,global positioning system (GPS)5 receivers,night-vision goggles,andother battery powered devices to get aroundand do their work.The backpackselectricity- generating feature coulddramatically reduce the amount of awearer’s load now devoted to spare batteries,report Rome and his colleaguesinthe Sept.9 Science6.

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

　　Unexpectedly,testsshowedthat wearers of the new backpack alter their gaits in response to thepacksoscillations,so that they carry loads more comfortably and with lesseffortthan they do ordinary backpacks.Because of that surprising advantage,Romeplans to commercialize both electric and non-electric versionsof the backpack.

　　The backpackcould be especially useful orsoldiers,scientists,mountaineers,and emergencyworkers who typically carryheavy backpacks.For the rest of us,power-generatingbackpacks could make itpossible to walk,play video games,watch TV,and listen tomusic,all at the sametime.Electricity-generating packs arent on the marketyet,but if you do get one eventually,just make sure to look both ways beforecrossing thestreet!

　　1.Backpacks are convenient because

　　答案： yourhands are freed to do other things.

　　2.What is the most important feature of the backpack invented byLawrence C.Romeand his colleagues?

　　答案： Itproduces electricity forelectronic devices while the wearer walks.

　　3.The word "springs" inParagraph 3 means .

　　答案： a lengthof metal woundaround,which returns to its original shape after

　　being pushed.

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

　　A To makethe backpackmore comfortable for the wearer.

　　答案： To putthe backpack on the market.

　　5.What isimplied in “if you do getoneeventually,just make sure to took both ways before crossing thestreet!"?

　　答案：Enjoyingelectronic devices while walking may invite traffic accidents.

小编：二月