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
2015-01-09
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 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.
What does Irvine-Halliday think of LEDs?
选项
A、They are cool and steady, but rugged.
B、They will replace Edison’s lightbulbs someday.
C、They are easily maintained.
D、They are very cheap.
答案
B
解析
第二段接着说,发光二极管比爱迪生的白炽灯具有更大的优越性,所以哈利德期待它能取代白炽灯成为世界的主要人造光源。
转载请注明原文地址:https://jikaoti.com/ti/ac6YFFFM
0
考博英语
相关试题推荐
CountrieswithintheEuropeanCommunitygrantcertaincommercial______toeachother.
WhenDonaldarrivedforhisfirstgroup-therapysessionhewasinawheelchair,sufferingfrommalignantmelanomaandseverelyd
WhenDonaldarrivedforhisfirstgroup-therapysessionhewasinawheelchair,sufferingfrommalignantmelanomaandseverelyd
Sometelevisionprogramshavetobefundamentallychangedonaccountofanindustrial______.
Writeacompositionofabout250wordsonthefollowingtopic.RemembertowriteyourcompositiononAnswerSheetII.
Readthefallowingparagraphandthenwritearesponsepaperofabout250to300Englishwords.WriteitneatlyonANSWERSHEET(
______Irealizedtheconsequences,Iwouldneverhavecontemplatedgettinginvolved.
Inthispart,youareaskedtowriteanessayaccordingtotheoutlinegiven.Yourcompositionshouldbeabout200words.Rememb
这次到台湾访问交流,虽然行色匆匆,但是,看了不少地方,访了旧友,交了新知,大家走到一起,谈论的一个重要话题就是中华民族在21世纪的强盛。虽然祖国大陆、台湾的青年生活在不同的社会环境中,有着各自不同的生活经历,但大家的内心都深深铭刻着中华文化优秀传统的印记,
每逢新年,人们往往要定新年决心(NewYearresolutions)。这是很多人下决心改变旧习惯、适应新的学习和生活方式的时刻。新年决心像其他很多时尚一样,说起来简单做起来难。通过艰苦工作和坚持不懈,把自己的目标、梦想、决心和远大期望变成现实真不是容
随机试题
高速旋转机械的起动试运转,开始时应做短时间试运转,并观察其转速逐渐( )所需的滑行时间。
在我国,一家同时经营海上国际货运代理业务和陆路国际货运代理业务的公司,其注册资本最低应为人民币()
牙槽骨吸收的诊断标准是()
A.执业药师B.药师及主管药师、主任药师C.医院药剂师D.临床药师E.从业药师我国对药学技术人员实行注册制度是
根据《建设工程项目管理规范》GB/T50326—2006,下列工作中属于施工方项目经理管理控制的是()。
生产农用运输车辆的江陵公司将柴油发动机的生产授权给一个供应商。下列各选项中,属于该公司货源策略优点的有()。
透视学、__________和__________是造型艺术的三大基础理论,或称“技法理论”。
[*]
Vacation(休假)timecanbeassimpleasjusttimeawayfromwork.Youmayjustwantto【C1】______homeanddonothing.Thereisnothi
使我感到惊奇的是,他的英语说得如此的好。
最新回复
(
0
)