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
86
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.
The passage implies that________.
选项
A、LED bulbs are still expensive at present
B、the task of making LED the main source of artificial light is too difficult
C、LED traffic lights are used everywhere in the world
D、in order to fulfill the task of making LED the main light source, lightbulb makers have to work together with semiconductor manufacturers
答案
A
解析
这道题需要分析判断。最后一段说,研制出节能,廉价,美观的白色发光二极管是一个艰巨的挑战。再联想到文章前面提到,美国的交通指示灯换上了节能耐用的二极管,而发展中国家还都用白炽灯。那么新能源的症结就是不廉价, 这一判断与选项A相符。
转载请注明原文地址:https://kaotiyun.com/show/PChO777K
0
考博英语
相关试题推荐
Awisemanoncesaidthattheonlythingnecessaryforthetriumphofevilisforgoodmentodonothing.So,asapoliceoffice
Cultureisactivityofthought,andreceptivenesstobeautyandhumanefeeling,【1】ofinformationhavenothingtodowithit.Am
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Thepatientisnotingoodcondition,sodonot______yourvisit.
ThebeginningofwhatwastobecometheUnitedStateswascharacterizedbyinconsistenciesinthevaluesandbehaviorofitspop
Cloningshakesusalltoourverysouls.Forhumanstoconsiderthecloningofoneanotherforcesthemalltoquestionthevery
Allofuswereimpressedbyher______complexion.
Newtechnologylinkstheworldasneverbefore.Ourplanethasshrunk.It’snewa"globalvillage"wherecountriesareonlyseco
Newtechnologylinkstheworldasneverbefore.Ourplanethasshrunk.It’snewa"globalvillage"wherecountriesareonlyseco
IntheUnitedStates,thefirstdaynurserywasopenedin1854.Nurserieswereestablishedinvariousareasduringthe【C1】______
随机试题
一分子乙酰CoA经有氧氧化(三羧酸循环)可生成几分子ATP
是药物进入体循环的量与所给剂量的比值称为是体内药量按血浆中同样浓度分布时所需体液的总体积为
下列关于工程项目人力资源管理中职责与角色关系的表述,正确的是()。
梁板预制完成后,移梁前应对梁板喷涂统一标识和编号,标识内容包括()。
受弯构件截面上通常有()作用。
后履行合同义务的一方当事人出现()情形时,先履行合同义务的当事人不得以此主张不安抗辩权。
逆向服务是在产品(服务)销售以后,企业向顾客提供实现产品(服务)使用价值的服务。根据上述定义,下列不属于逆向服务的是:
根据下列给定材料,结合相关法律规定,回答问题。泰嘉贸易公司从国外购进100吨钢材,委托某船运公司运往中国境内。一日,该船运公司一艘货船夹载着该船船员私自在国外购买的500多件电器等物,在中国海口市担杆岛附近海域进行走私交易时,被中国某海关抓获。该
检查软件产品是否符合需求定义的过程称为______。
A、 B、 C、 C原文说“David喜欢听收音机”,所以[C]是正确的。
最新回复
(
0
)