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
85
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
WhenIwaswalkingdownthestreettheotherday,Ihappenedtonoticeasmallbrownleatherwalletlyingonthesidewalk.Ipic
"Blockpatrol(巡逻,巡逻队),""communitywatch""civilianpatrol."Theymayhavedifferentnamesindifferentcitiesacrossthe
OnesillyquestionIsimplycannottolerateis"Howdoyoufeel?"Usuallythequestionisaskedofamaninaction—amanwalking
Clothestellusagooddealaboutthewearer’sbackground,personality,status,moodandoutlookonlife.Peopletendtoagr
AsnooneinthesmallvillageknewnothingaboutMedicine,Mrs.Smith,aformernurse,hadtoworkasadoctor.
——你们班谁最年轻?——小李,他还是班上最优秀的学生。
You’11havenothingto______ifyourefusetolistentoouradvice.
Ithink______righttotellherthetruth.
Ihopeyouwon’tmind______youthetruth.
随机试题
上唇正中唇红向前下方突出的结节为()
霍乱临床治疗的原则为
在确认计量结果后()天内,发包人应向承包人支付工程款。
验货付款的期限为7天,(收付合同中约定的应当从其约定)自运输部门向付款人发出提货通知的次日算起。()
植物羊皮纸,宽30厘米,成卷
某公司年终利润分配前的股东权益项目资料如下:股本——普通股(每股面值2元,200万股)400万元资本公积
土地增值税的纳税人,应于()向主管税务机关申报纳税。
位于某市区的一家房地产开发公司,2008年度开发建设办公楼一栋,12月与某生产性外商投资企业签订一份购销合同,将办公楼销售给该生产性外商投资企业,销售金额共计1200万元。合同载明,外商投资企业向房地产开发公司支付货币资金900万元,另将一块未作任何开发的
班主任带好班级应做到()。
下列叙述中,正确的是
最新回复
(
0
)