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
2012-07-18
140
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 amount 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
文章第一段说,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://kaotiyun.com/show/cKnO777K
0
考博英语
相关试题推荐
MATRIX:NUMBERS
Fromthehealthpointofviewwearelivinginamarvelousage.Weareimmunizedfrombirthagainstmanyofthemostdangerousd
WhenyouwatchafootballgameonaSaturdayafternoon,youfeelsecureinyourknowledgeofwhatwillhappenwhenaplayerboot
Althoughherresearchtopichadbeenapprovedbyherthesisadvisor,thelibrarypersistedin______thedocuments.
Complacencytowardsecologicalbalance("Itcan’thappenhere!")hasresultedinanumberof______.
Chimpanzeesarefrequentlyusedasstand-insforhumanbeingsinexperiments.
Bothaperson’sheredityandhisenvironmenthelptoshapehischaracter.
TheCommitteepronouncedfourmembersexpelledforfailuretoprovideinformationinthe______ofinvestigations.
Whendepositsarefederallyinsured,peoplenolongerrushtowithdrawtheirmoneyifthey______thefinancialconditionoftheir
I’msorrytoinformyouthatyourapplicationhasbeendeclined.Ourmanagerthoughtyouwerenot______forthepost.
随机试题
因不可抗力耽误法定申请期限的,申请期限自障碍消除次日起继续计算。()
某企业近期向市儿童福利院无偿捐赠人民币10万元,为听力障碍儿童购买助听器,以展示企业社会责任。该企业的捐款动机属于()。
Iamoftenaskedtodescribetheexperienceofraisingachildwithadisability.Itislikethis.【C1】______youaregoingtohav
肛裂最主要的症状是
有效控制工程造价应体现以()为重点的建设全过程造价控制。
背景资料:A施工单位承建某新建单线铁路隧道,隧道全长1280m。根据设计图纸,进口段50m埋置较深,出口段30m埋置较浅,设计围岩级别均为Ⅴ级,石质比较破碎。洞身部分除进、出口段外围岩级别主要为Ⅱ级,局部节理较发育地段围岩级别为Ⅲ级,地下水不发
汇票的三个基本当事人,包括付款人、收款人和()。
确立和实践社会主义核心价值体系,必须以全体社会成员的法制意识为基础。()
窗体上有一个名称为Text1的文本框,一个名称为Command1的命令按钮。要求编写一个程序,统计文本框中0-9各数字字符的个数。某人编写如下程序:PrivateSubCommand1_Click()Dimcount(10)AsInt
Forthispart,youareallowed30minutestowriteacompositionentitledShouldGraduatesSpendMuchonJobhunting?Youshould
最新回复
(
0
)