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
What do cats’ eyes and highway reflector signs have in common? They both act as retro-reflectors(反响反射器). Almost everyone has
What do cats’ eyes and highway reflector signs have in common? They both act as retro-reflectors(反响反射器). Almost everyone has
admin
2013-12-08
87
问题
What do cats’ eyes and highway reflector signs have in common? They both act as retro-reflectors(反响反射器).
Almost everyone has noticed the frightening appearance of animals at night, as their eyes seem to glow in reflected light. One may think that just as reflective highway signs alert the motorists to many road hazards, so early man was often warned of danger by light from his campfire reflected in the eyes of lurking(潜伏)predators. In both cases, the light is ret-roreflected, giving it a particularly bright appearance.
The principles of retroreflection have been understood for centuries. However, it is only within the last fifty or sixty years, with the wide use of the automobile, that this area of optics(光学)has received important commercial application. Today, the uses of retroreflective materials are many. They are applied to bicycles and motor vehicles to make them more visible at night. And they assist pilots by improving the visibility of runway markers.
Large sums are spent for retroreflective materials, but purchasers have often found it difficult to specify performance for the materials they buy. Performance is of concern not only from the standpoint of the brightness of reflected light, but also from the standpoint of its color. It is important, for example, that the yellow hues(色调)in warning signals be of consistent color quality on all road signs so the driver can rely on color, as well as shape, to discern the signs’ meanings. Seven colors — silver, blue, yellow, red, green, brown and orange — are currently used for marking the interstate highway system.
Retroreflective materials have been used extensively since the invention of______ .
选项
A、the automobile
B、the laser beam
C、photography
D、highways
答案
A
解析
本题属于事实细节题,提问的是反向发射器在什么发明以后才被广泛应用。依据是第三段前两句,人们了解反向反射原理虽然已有数百年,但直到汽车被广泛使用,它才具有了重要的商业用途。这说明,反向反射材料的广泛应用是从汽车被发明之后才开始的。所以答案为A)。
转载请注明原文地址:https://kaotiyun.com/show/zyDO777K
0
成人本科学位英语
相关试题推荐
Cyberspace(网络空间),datasuperhighways,multimedia—forthosewhohaveseenthefuture,thelinkingofcomputers,televisionand
WhoarethepoorintheUnitedStates?Asof1970,nearlytwo-thirdsofthepoorpeoplewerewhite.Althoughnonwhitesmakeupo
Peoplehavewonderedforalongtimehowtheirpersonalitiesandbehaviorsareformed.Itisnoteasytoexplainwhyoneperson
Lifereallyshouldbeonelongjourneyofjoyforchildrenbornwithaworldofwealthattheirfeet.Internationallyfamous
Thefamilyisasocialinstitution.Theimportanceofthefamilyinanindividual’slifeusuallydependsonthesizeofthesoci
Anallowance(零花钱)isanimportanttoolforteachingkidshowtobudget,saveandmaketheirowndecisions.Childrenrememberan
Veryfewwilldoubtthatitissciencethathasatoncequickenedthedemandforgeneraleducationinmoderntimes______madethe
______fromthetopofthemountain,thewholecitylooksbeautiful.
Themansaidthathewasnotguilty______thecrime.
Hegotuptotheroof______aladder.
随机试题
关于颈部CT增强扫描技术,叙述错误的是
甲公司与乙公司签订委托合同,由甲公司委托乙公司采购某型号100台电机,并预先支付购买电机的费用50万元。乙公司经考察发现A市x区的丙公司有一批质优价廉的名牌电机,遂以自己的名义与丙公司签订了一份电机买卖合同,双方约定:乙公司从丙公司购进100台电机,总价款
采用蒸汽直接通入水中的加热方式时,下列叙述正确的是()。
大地水准面具有的特点是()。[2010年真题]
以下各项中不属于公文版头部分的结构要素是()。
下列哪些行为构成妨害公务罪?()
下列关于单位犯罪的说法中,错误的有()
要建立文件流并打开当前目录下的文件file.dat用于输人,下列语句中错误的是()。
在数据表视图下向表中输入数据,在未输入数值之前,系统自动提供的数值字段的属性是【】。
HowTwoGreatConflictsHelpedtoChangeEuropeNinetyyearsagoonasunnymorninginNorthernFrance,somethinghappenedt
最新回复
(
0
)