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
2011-01-05
35
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. 9 Science.
The backpack’s electricity-crew, ring 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
转载请注明原文地址:https://www.kaotiyun.com/show/Hqhd777K
本试题收录于:
职称英语理工类基础题库职称英语分类
0
职称英语理工类基础
职称英语
相关试题推荐
Sincewearesocialbeings,thequalityofourlivesdependsinlargemeasureonourinterpersonalrelationships.Onestrengtho
CollegeNightOwlsHaveLowerGradesCollegestudentswhoaremorningpeopletendtogetbettergradesthanthosewhoareni
CollegeNightOwlsHaveLowerGrades Collegestudentswhoaremorningpeopletendtogetbettergradesthanthosewhoarenig
ActiveinOldAgeKeepsPeopleMobilePeopleover70whoaren’tactivearemorelikelytodevelopproblemswalkingorclimbi
Jennywasaveryambitiousandenergeticperson.Shedidn’thavemuchincommonwithothergirlsinherschool,however.Shepla
AthatmaycauseourbloodvesselstobecomemoreandmorenarrowBforpregnantwomentotakeduringtheirlastsixmonthsofp
7.Inabullfight,itisthemovement,notthecolorofobjectsthatarousesthebull.
Thepresidentproposedthatweshouldbringthemeetingtoaclose.
AIntroductiontoSingaporeBEducationCEconomyDStateSystemofSingaporeEHistoryofSingaporeFLandandClimate
Jackwasdismissed.
随机试题
极大似然估计【】
___________是一个供用户输入字符的文本框,用于在计算机上快速查找程序、文件和文件夹。
下列属于常用的操作系统的是_________。
下列哪种激素的受体属于酪氨酸蛋白激酶受体
设,若f(x)在x=0处可导,则a=( )。
存货是指企业在正常生产经营过程中()。
某公司是一家成立时间不长,但发展迅速的民营公司,随着市场拓展和员工数量的增加,公司最近成立了人力资源部,希望能专业化地开展人员的聘用和绩效考核工作。解决人员配置和绩效管理等方面存在的突出问题,人力资源部张经理为了更好的解决人力资源管理方面的问题,首先要开展
按照ABC分类法进行库存控制,B类物资具有的特征是()。
根据保险法律制度的规定,下列不属于保险人可以单方解除合同的情形有()。
做学问,“要大处着眼,小处下手”,由博人专,不可急功近利。能大处着眼,为学方不致流于______,而有裨益于世:能小处下手,方不致流于_______。所以做学问千万不要求速效。填入画横线部分最恰当的一项是:
最新回复
(
0
)