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
A、Workers on the platforms and trains were replaced by machines. B、A completely automatic line was added to its network. C、It be
A、Workers on the platforms and trains were replaced by machines. B、A completely automatic line was added to its network. C、It be
admin
2012-12-13
63
问题
The world’s first completely automatic railway has been built under the busy streets of London. The railway is called the Victoria Line, and it is part of the complete London underground railway.
The new Victoria Line was opened in 1969. This new line was very different from the others. The stations on the other lines need a lot of workers to sell tickets, and to check and to collect them when people leave the trains. This is all different on the Victoria Line. Here a machine checks and collects the tickets, and there are no workers on the platforms.
On the train, there is only one worker. If necessary, this man can drive the train. But usually he just starts it; it runs and stops by itself. The trains are controlled by electrical signals which are sent by the so-called "command spots".
The command spots are the same distance apart. Each sends a certain signal. The train always moves at the speed that the command spots allow. If the command spot sends no signals, the train will stop.
Most of the control work is done by computers. The computers also fix the train’s speeds, and send the signals to the command spots.
Other machines make sure that the trains are always a safe distance apart. One train may stay too long at a station; the other trains will then automatically move slower. So there is no danger of accidents on the line.
选项
A、Workers on the platforms and trains were replaced by machines.
B、A completely automatic line was added to its network.
C、It became the first completely automatic railway in the world.
D、Its trains became manual-controlled.
答案
B
解析
What happened to the complete London underground railway thirty-nine years ago?
转载请注明原文地址:https://kaotiyun.com/show/apb7777K
0
大学英语六级
相关试题推荐
Thestudentsenatewillsupportsupervisors’actionsiftheyare______withtheestablishedstudentsenatepoliciesandprocedu
Attemptstorestrictparkinginthecitycenterhavefurther_________theproblemoftrafficcongestion,andsometimesthetraf
Theschool______apublicdebateonwhethertheyshouldbuildanewcomputerlaboratoryornot.
Whenlightilluminatesanobject,partofitisabsorbedandpartreflected,the________lightnessofanobjectdependsonthep
Heisa______person.Herarelyacceptsanybody’sopinionwithoutquestioningit.
Somejournalistsoftenoverstatethesituationsothattheirnewsmaycreateagreat________.
TheEnglishlanguagecontainsa(n)______ofwordswhicharecomparativelyseldomusedinordinaryconversation.
A、BehostiletoNancy.B、AskNancytocomeout.C、TalktoNancyherself.D、WriteNancyaletter.C对话中男士提到comingrightoutandas
Thepast50yearshaveseenmassiveexpansionofagriculture,withfoodproductionmorethandoublinginordertomeetdemand.B
A、Sheshouldfollowthehumannature.B、Strangersarenothingtobeafraidof.C、Feelingnervousisnothingimproper.D、Sheshou
随机试题
A.非甾类抗炎药B.合成雌激素代用品C.孕激素类药物D.雄激素类药物E.肾上腺皮质激素类药物黄体酮属于
贮藏中易泛油的药材有
A.腹痛B.黑便C.皮炎D.性功能减退E.便秘枸橼酸铋钾所致的主要不良反应是()。
【背景资料】某群体工程,主楼地下2层,地上8层,总建筑面积26800m2,现浇钢筋混凝土框架结构,建设单位分别与施工单位、监理单位按照《建设工程施工合同(示范文本)》(GF一2013—0201)、《建设工程监理合同(示范文本)》(GF一20
财政直接支付的中请由一级预算单位汇总,填写《财政直接支付申清书》,报财政部同库支付执行机构。()
某酒厂2016年1月份生产一种新的粮食白酒,广告样品使用0.4吨,已知该种白酒无同类产品出厂价,生产成本为每吨42000元,成本利润率为10%,白酒定额税率为每500克0.5元,比例税率为20%。该酒厂当月应缴纳的消费税为()元。
最早提出“什么知识具有价值”的是()。
民法典的编纂模式主要有
已知函数f(x)=在x=0处连续,求未知参数a的值。
Whatisthemainideaofthenewsitem?
最新回复
(
0
)