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
34
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
EvolutionofSleepSleepisveryancient.Intheelectroencephalographic(脑电图)senseweshareitwithalltheprimates(灵长类)a
F.D.RooseveltWhenPresidentFranklinD.RooseveltcollapsedanddiedofastrokeinApril12,1945,thenationwentinto
Smokingisconsidereddangeroustothehealth.Ourtobacco--seller,Mr.Johnson,therefore,alwaysaskshiscustomers,iftheya
WhatMakesMetheWeightIAm?There’snoeasyanswertothisquestion.Yourgeneticmakeup,thephysicaltraitsthatgetp
ActiveinOldAgeKeepsPeopleMobilePeopleover70whoaren’tactivearemorelikelytodevelopproblemswalkingorclimbi
She’sahighlyoriginalyoungdesigner.
Timeisveryimportantinourlives.Itorganizesoureverydaymoments.However,timeneverhadanyimportanceinmylifeuntil
AIntroductiontoSingaporeBEducationCEconomyDStateSystemofSingaporeEHistoryofSingaporeFLandandClimate
Theyhavebeentighteningtheirbeltsformonths,adaptingthemselvestoawareconomy.
SleepSmartisaclockthatTheideaofmakingsuchaclockwasdevelopedbyagroupof
随机试题
胰腺CT的扫描范围为
《建设项目竣工环境保护验收技术规范一生态影响类》规定了生态影响类建设项目竣工环境保护验收调查()。
项目准备阶段的咨询包括()
某市建筑集团公司承担一栋20层智能化办公楼工程的施工总承包任务,层高3.3m,其中智能化安装工程分包给某科技公司施工。在工程主体结构施工至第18层、填充墙施工至第8层时,该集团公司对项目经理部组织了一次工程质量、安全生产检查。部分检查情况如下:(1)现场
在会计职业道德规范中,坚持准则的基本要求是熟悉准则、遵循准则和坚持准则。()
在计算外商投资企业和外国企业所得税时,下列说法正确的是( )。
基督教起源于公元1世纪亚洲西部巴勒斯坦地区的犹太人中间。()
行政性督导工作中督导者扮演的角色有()
一般认为,剑乳齿象是从北美迁入南美洲的。剑乳齿象的显著特征是具有较真的长剑形门齿,颚骨较短,臼齿的齿冠隆起,齿板数目为7~8个,并呈乳状凸起,剑乳齿象因此得名。剑乳齿象的牙齿结构比较复杂,这表明它能吃草。在南美洲的许多地方都有证据显示史前人类捕捉过剑乳齿象
CompletethesentencesbelowwithwordstakenfromReadingPassage1.UseNOMORETHANTHREEWORDSforeachanswer.Writeyoura
最新回复
(
0
)