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
To get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found vil
To get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found vil
admin
2013-11-29
30
问题
To get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found villagers working and reading around battery-powered lamps equipped with light-emitting diodes, or LEDs — the same lamps he had left there in 2000.
Irvine-Halliday, an American photonics engineer, was not surprised. He chose to use LED bulbs because they are rugged, portable, long-lived, and extremely efficient Each of his lamps produces a useful a-mount of illumination from just one watt of power. Villagers use them about four hours each night, then top off the battery by pedaling a generator for half an hour. The cool, steady beam is a huge improvement over lamps still common in developing Countries. In fact, LEDs have big advantages over familiar incandescent (白炽的) lights as well — so much so that Irvine-Halliday expects LEDs will eventually take over from Thomas Edison’s old lightbulb as the world’s main source of artificial illumination.
The dawn of LEDs began about 40 years ago, but early LEDs produced red or green glows suitable mainly for displays in digital clocks and calculators. A decade ago, engineers invented a semiconductor crystal made of an aluminum compound that produced a much brighter red light Around the same time, a Japanese engineer developed the first practical blue LED. This small advance had a huge impact because blue, green, and red LEDs can be combined to create most of the colors of the rainbow, just as that in a color television picture.
These days, high-intensity color LEDs are showing up everywhere such as the traffic lights. The reasons for the rapid switchover are simple. Incandescent bulbs have to be replaced annually, but LED traffic lights should last five to yen years. LEDs also use 80 to 90 percent less electricity than the conventional signals they replace. Collectively, the new traffic lights save at least 400 .million kilowatt-hours a year in the United States.
Much bigger savings await if LEDs can supplant Mr. Edison’s bulb at the office and in the living room. Creating a white-light LED that is energy-saving, cheap and appealing has proved a tough engineering challenge. But all the major lightbulb makers — including General Electric, Philips, and Osram-Sylvania — are teaming up with semiconductor manufacturers to make it happen.
From the first paragraph, we can see that Dave Irvine-Halliday________.
选项
A、is a mountain climber
B、went to that village to repair the lamps
C、found the villagers were using the lamps he had given them
D、has visited the small village several times
答案
C
解析
文章第1段说,当哈利德到达尼泊尔遥远的小村庄时,他发现村民们正用他留给他们的发光二极管的灯来工作和学习。
转载请注明原文地址:https://jikaoti.com/ti/fGOYFFFM
0
考博英语
相关试题推荐
Atthefall2001SocialScienceHistoryAssociationconventioninChicago,theCrimeandJusticenetworksponsoredaforumonth
BetweentheinventionofagricultureandthecommercialrevolutionthatmarkedtheendoftheMiddleAges,wealthandtechnology
Thetextureofthesoildependsontherelativeamountsofdifferent-sizedparticlesthatcombinetomakeupthesoil.Thesepar
Thetextureofthesoildependsontherelativeamountsofdifferent-sizedparticlesthatcombinetomakeupthesoil.Thesepar
ThepoliticalcrisisinUkraine,whereoppositionprotestersareburningcampfiresandsettinguptentsinthecenterofKiev,i
Nowadays,thegoalsofAlma-Ataseemevenmoredistantthantheywereaquarterofacenturyago.Deepeconomicinequalitiesand
Therearemanybenefitstousingonlinedistancelearningenvironments.Onlineeducationisavailableanyplace,anytimeforgl
TheAlaskapipelinestartsatthefrozenedgeoftheArcticOcean.Itstretchessouthwardacrossthelargestandnorthernmosts
Cloningshakesusalltoourverysouls.Forhumanstoconsiderthecloningofoneanotherforcesthemalltoquestionthevery
IntheUnitedStates,thefirstdaynurserywasopenedin1854.Nurserieswereestablishedinvariousareasduringthe【C1】______
随机试题
通常所说的ADSL是指________。
1953年9月,毛泽东在对民主党派和工商界部分代表讲话时指出:改造资本主义工商业和逐步完成社会主义过渡的必经之路是()
为实现进度目标,不但应进行进度控制,还应注意分析影响工程进度的风险,并在分析的基础上采取( ),以减少进度失控的风险量和常见的影响工程进度的风险。
在编制机械台班使用定额时,下列属于机械工作必需消耗时间的是()。
网址主要有()表示方法。
单位将自产、委托加工和购进的货物用于下列项目时,应征收增值税的是()。
根据营改增的有关规定,下列各项中,属于文化创意服务的有()。
请简要说明劳动者派遣的成因和特点。
参加党课学习,共同( )政治理论和党的基本知识成了大学生们课余活动的重要内容之一。
以下关于知觉的信息加工说法正确的是()
最新回复
(
0
)