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
For centuries men dreamed of achieving vertical flight. In 400 A. D. Chinese children played with a fan-like toy that spun upwar
For centuries men dreamed of achieving vertical flight. In 400 A. D. Chinese children played with a fan-like toy that spun upwar
admin
2010-03-26
58
问题
For centuries men dreamed of achieving vertical flight. In 400 A. D. Chinese children played with a fan-like toy that spun upwards and fell back to the earth as rotation ceased. Leonardo da Vinci conceived the first mechanical apparatus, called a "Helix", which could carry a man straight up, but this was only a design and was never tested.
The ancient dream was finally realized in 1940 when a Russian engineer piloted a strange looking craft of steel tubing with a rotating fan on top. It rose awkwardly and vertically into the air from a standing start, hovered a few feet above the ground, went sideways and backwards, and then settled back to the earth. That vehicle was called a helicopter.
Imaginations were fired. Men dreamed of going to work in their own personal helicopters. People anticipated that vertical flight transports would carry millions of passengers as do the airliners of today. Such fantastic expectations were not fulfilled. The helicopter has now become an extremely useful machine. It excels in military missions, carrying troops, guns and strategic instruments where other aircraft cannot go. Corporations use them as airborne offices, many metropolitan areas use them in police work, construction and logging companies employ them in various advantageous ways, engineers use them for site selection and surveying; and oil companies use them as the best way to make offshore and remote work stations accessible to crews and supplies. Any urgent mission to a hard-to-get-to place is a likely task for a helicopter. Among their other multitude of uses: deliver people across town, fly to and from airports, assist in rescue work, and aid in the search for missing or wanted persons.
How has the use of helicopters developed?
选项
A、They are taking the place of high-flying jets.
B、They are used for rescue work only.
C、They have been widely used for various purposes.
D、They are now used for commercial purposes.
答案
C
解析
最后一段整段都用来说明直升飞机的用途,可见其用途之广。因此,正确答案是C项。
转载请注明原文地址:https://kaotiyun.com/show/5Xk7777K
0
大学英语四级
相关试题推荐
Whymoreandmorepeoplebecameinterestedinbecomingcomputerprogrammers?Whatcanweinferfromthispassage?
Whymoreandmorepeoplebecameinterestedinbecomingcomputerprogrammers?Whichisnotmentionedasthecharacteristicsofp
Whilemostpeoplethinkoftheprototypicalgeek(表演滑稽戏的人)whendefiningcomputerprogrammers,thefieldisbecomingmorediverse
RuthAnnandRobertLipicknewtheirchildrencouldmakemistakesthatcouldlastalifetime—maybeevenshortenalifetime.Asf
ThedisputeonDPRK’snuclearprogrammeissuegivesanegativeinfluenceonUS-DPRKrelations.TheUSgovernment’s"softpower"
ThedisputeonDPRK’snuclearprogrammeissuegivesanegativeinfluenceonUS-DPRKrelations.ConfrontationhasdominatedSino
Mathematics,physics,chemistryandChinese—_________________(我都感兴趣).
Bynowyouknowthat【B1】yourmoney’sworthisnotjustamatterofluck.Itismoreoftenthe【B2】ofbuyingskill.【B3】,eventhe
A、LetTeachersStopWork.B、LetusMakeChildrenLearn.C、LetChildrenCorrectTheirExercises.D、LetChildrenLearnbyThemselv
A、Shethinksitisagreatidea.B、Shethinksitisnogoodforstudents’study.C、Shethinksithasitspositivesideaswella
随机试题
建筑物内设备隔振不仅有效降低震动干扰,而且对降低哪种声波也有良好效果?[2006年第11题]
社会主义经济制度的本质特征是()
下列哪种情况可引起全身淋巴结肿大
男,76岁,高血压30余年,平时血压在150~180/90~110mmHg,不规则服用降压药。2周来胸闷、气促,贫血貌,颈静脉怒张,心界向左下扩大,心率104次/分,二肺底有细小湿啰音,肝肋下二指,下肢水肿++,尿蛋白+,血肌酐884μmol/L(10m
国家为了公共利益的需要,可以依照法律规定对集体所有的土地实行征用。征用土地的特点表述正确的是()。
根据《关于加强规划环境影响评价与建设项目环境影响评价联动工作的意见》,下列规划中,属于可以实施规划环评与规划包含的项目环评联动工作的是()。
对于要求空间布置灵活、抗震性能好的高层建筑,常采用()结构。
供应商感知模型中,决定非货币因素吸引力大小的因素包括()。
下列关于软件的叙述中正确的是()。
A、Areport.B、Abookreview.C、Aresearchstudy.D、Aten-pagecomposition.A选项中的report,review,ten-pagecomposition等表明,本题可能与课程作业或
最新回复
(
0
)