In the past,telephone calls were made mostly over copper wires.Copper wires are heavy and bulky.Fiber optics are flexible,glass fibers.They are no thicker than a human hair.A wire cable is as thick as a mans arm.An optical fiber cable is as thick as a thumb.
Fiber optics transfer sound into light.First,a person speaks into a phone.The sound is changed into electrical impulses.A small laser changes the electrical impulses into coded bursts of light.The light is decoded hack into electrical impulses at the telephone recieving station.Finally,the electrical impulses are changed into sounds again at the receiving telephone.
Optical fibers transimit calls much faster than copper wires can.The laser pulses with light as fast as 90 million times a second.At that speed,every word in a dictionary can be sent through a single fiber in a few seconds.Optical fibers also save space.A few fibers can carry more calls than thousands of strands of copper cable.
Optical fibers will be used for video as well as voice communications.And they will prove useful in computer-to-computer hookups.However,it will take years to replace existing wires.
1.Which of the following best expresses the main point of the passage?
a.Fiber optics are flexible,glass fibers.
b.Copper wires have been used in most phone systems.
c.Fiber optics are an improvement in communication systems.
d.A few optical fibers can carry thousands of phone calls.
2.As it is used in the passage,the phrasefiber opticsmeans _____.
a.transmission of information by means of infra-red light signals aling a thin glass fiber.
b.material or substance formed from a mass of fibers.
c.a flexible fiber-optic instrument that is used to view objects
d.a composite material consisting of glass fibers in resin
3.Which of the following can not be inferred about fiber cables from the passage?
a.They carry light waves.
b.They can be used in many forms of communication.
c.They are better than copper wires.
d.They are shorter than copper wires.
4.You can infer from the passage that a cable is _____.
a.a group of wires or strands that are bundled together
b.a copper wire that is used to carry phone calls
c.a glass fiber that carrise coded bursts of light
d.a laser that changers electrical impulses into light
5.You can infer from the passage that the wordtransmit most nearly means _____.
a.carry from one place to another
b.pulse with light
c.operate quickly
d.speak
答案:cadaa
美国单身母亲终于找到好归宿:嫁给自己
测一测!办公桌告诉你,你是哪类职场怪咖
国内英语资讯:Development master key to solving all problems: Chinese FM
上海迪士尼今天开始售票!看点攻略票价全知道
职场必备的软技能有哪些?
中国网络红人papi酱获1200万元投资
国内英语资讯:President Xi to grant national medals and honorary titles
意大利孕妇坐公交可凭徽章“求让座”
新西兰公投:银蕨星旗落败 将沿用米字国旗
快乐很简单:20个提升幸福指数的小瞬间
英国女王为啥能一直站在时尚潮流尖端?
国际英语资讯:China-Philippines relations have moved forward steadily, delivered tangible outcomes: Chines
国际英语资讯:UN rights session adopts resolution to mark 25th anniversary of the Beijing Declaration
撒贝宁领证结婚:跨国婚姻英文怎么说?
体坛英语资讯:Serbia, Spain meet no challenge, China grabs first home win at FIBA World Cup
幸福的人都在做这8件事
你属于哪种胸型 你真的选对文胸了吗?
Siri的9大酷炫技能 Siri给我讲个笑话吧
外媒:成功女性的34个标准 你做到几点
国际英语资讯:Libyas UN-backed govt forces launch airstrikes on eastern-based army in southern Tripoli
中捷合拍动画片《熊猫和小鼹鼠》开播
为什么你减肥总是不成功?警惕这十大绊脚石
轰动全球的埃及劫机 竟是个悲伤的爱情故事
70年来,国人都学过这些英语教材......有你的那版吗?
研究显示:名字或能影响一个人的寿命
研究警告:新车“香味”有毒!
2016年春季5大时尚新风潮
月薪多少能撑一个家?收入最高国家TOP10盘点
研究显示:适量巧克力可促进大脑认知功能
高洪波:是否留任将于四月底揭晓
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |