首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Electric Backpack Backpacks are convenient. They can hold your books, your lunch, and a change of clothes, leaving your hand
Electric Backpack Backpacks are convenient. They can hold your books, your lunch, and a change of clothes, leaving your hand
admin
2013-11-20
73
问题
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!
Backpacks are convenient because______.
选项
A、they can be very large
B、they can hold as many things as you want to carry
C、your hands are freed to do other things
D、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。
转载请注明原文地址:https://kaotiyun.com/show/h4Qd777K
本试题收录于:
职称英语理工类B级题库职称英语分类
0
职称英语理工类B级
职称英语
相关试题推荐
ExerciseWhetherornotexerciseaddstothelengthoflife,itiscommonexperiencethatacertainamountofregularexerci
TeachingandLearningMedicineAwardTwoscientistswhohavewonpraiseforresearchintothegrowthofcancercellscouldb
Thehouseisfilledwithcrevicesduetotheattackingoftheearthquaketothecitylastnight.
AdaptationofLivingThingsCertainanimalsandplantsdevelopcharacteristicsthathelpthemcopewiththeirenvironmentbe
FactsaboutStroke1Every45seconds,someoneinAmericahasastroke.Every3.1minutes,someonediesofone.Strokekilled
ScientistsDevelopWaysofDetectingHeartAttackGermanresearchershave(1)anewgenerationofdefibrillatorsandearlywarn
Diabetes(糖尿病)andEyeDamageOver2millionCanadianshavediabetes.ItistheleadingcauseofblindnessinNorthAmerica
The20patientshadstemcellinjectionsinsteadofsurgery.Thecontrolgrouppatientsregrettednothavinghadstemcellinje
RealityandPerceptionofPersonality1.Exceptyourbelovedwhosefaceyoumighthavelookedatmanytimesveryclosely,looka
Ifeelregretaboutwhat’shappened.
随机试题
女性,54岁。优秀话务员,近几年怀疑丈夫有外遇,看电视时激动,控制不住,外出走失1周找不到自己家,住在露天,公安人员收留送回家,吃饭用手抓着吃,记忆力下降,行为幼稚。既往高血压7年,脑梗死后10个月,神经系统检查:BP225/110mmHg,说话口齿不清,
Forinstance,wheninanewsituation,anintelligentpersonthinksaboutthesituation,notabouthimselforwhatmighthappent
特发性血小板减少性紫癜的主要出血部位是
建筑安装工程费用定额一般包括()。
某项贷款年利率为8%,银行要求的补偿性余额维持在25%水平基础上。那么该贷款的实际利率是()。
一、注意事项1.申论考试与传统的作文考试不同,是分析驾驭材料的能力与表达能力并重的考试。2.作答参考时限:阅读资料40分钟,作答110分钟。3.仔细阅读给定的资料,按照后面提出的“申论要求”依次作答在答题纸指定位置。4.答题时请认准题号,避免答错位
某刑事人类学家在对260名杀人犯的外貌进行了考察后,发现他们具有一些共同的生理特征,于是得出“杀人犯具有广颚、颧骨凸出、头发黑而短特征”的结论。以下哪项与上述推理方式相同?
研究表明,高胆固醇高脂肪的饮食习惯能够导致心脑血管疾病。法国人喜欢美食,吃的高胆固醇高脂肪的食物不少,比如鹅肝、鱼子酱,得心血管疾病的比例却比其他国家要低—这个现象被称为“法国悖论”。以下哪项如果为真,最无助于解释“法国悖论”?
Howlongyoulivehasalottodowithyourenvironmentandlifestyle,butexceptionallongevitymayhaveevenmoretodowithy
Inthissection,youareaskedtowriteanessaybasedonthefollowingtable.Describethetableandstateyouropinion.Yoush
最新回复
(
0
)