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  3. 共用题干 第二篇Electric BackpackBackpacks are

共用题干 第二篇Electric BackpackBackpacks are

恬恬2019-12-17  18
问题 共用题干第二篇

Electric Backpack

Backpacks are convenient. They can hold your books,your lunch,and a change of clothes,leaving your
hands free to do other things.Someday,if you don't mind carrying a heavy load,your backpacks might also
power your MP3 player,keep your cell phone running,and maybe even light your way home.
Lawrence C.Rome and his colleagues from the University of Pennsylvania in Philadelphia and the
Marine Biological Laboratory in Woods Hole,Mass.,have invented a backpack that makes electricity from
energy produced while its wearer walks.In military actions,search-and-rescue operations,and scientific field
studies,people rely increasingly on cell phones,global positioning system(GPS)receivers,night-vision
goggles,and other battery-powered devices to get around and do their work. The backpack's electricity-generating
feature could dramatically reduce the amount of a wearer's load now devoted to spare batteries,report Rome
and his colleagues in the Sept.Science.
The backpack's electricity-creating powers depend on springs used to hang a cloth pack from its metal
frame.The frame sits against the wearer's back,and the whole pack moves up and down as the person
walks.A gear mechanism converts vertical movements of the pack to rotary motions of an electrical generator,
producing up to 7.4 watts.
Unexpectedly tests showed that wearers of the new backpack alter their gaits in response to the pack's
oscillations,so that they carry loads more comfortably and with less effort than they do ordinary backpacks.
Because of that surprising advantage,Rome plans to commercialize both electric and non-electric versions of
the backpack.
The backpack could be especially useful for soldiers,scientists,mountaineers,and emergency workers
who typically carry heavy backpacks.For the rest of us,power-generating backpacks could make it possible to
walk,play video games,watch TV,and listen to music,all at the same time.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
the street!
选项 Backpacks are convenient because_____________.A:they can be very largeB:they can hold as many things as you want to carryC:your hands are freed to do other thingsD:you do not have to carry things with you
答案C
解析第一段告诉我们，因为背包可以装许多东西，所以可以将双手解放出来做其他事情。 第二段的第一句说，Lawrence C.Rome及其同事们发明的这种背包，当背着背包走路时，会有电能产生；该段最后一句告诉我们，背包的这种性能可减少背包的重量，因为不必携带备用电池。 “springs”在此是“弹簧”的意思。spring是一个多义词：泉水（A）、春天（B）、弹跳（C）。 第四段最后一句的意思是：Rome计划将这种背包商业化，即推向市场。A项不是Rome 的计划，C、D两项在文中均未提到。D项的意思是为背包做广告。 这个句子的字面意思是：如果你终于得到这样的背包，过马路时一定要两边都看看。 也就是说，不要因为同时玩着游戏，听着音乐、看着电视，太专注以致不注意来往车辆了。第三篇 本文主要介绍了一种预刚山体滑坡的设备。
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