首页
登录
职称英语
For centuries men dreamed of achieving vertical flight. In 400 AD Chinese ch
For centuries men dreamed of achieving vertical flight. In 400 AD Chinese ch
游客
2023-07-27
14
管理
问题
For centuries men dreamed of achieving vertical flight. In 400 AD Chinese children played with a fanlike toy that spun upwards and fell back to 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 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 airlines 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. [br] What is a "Helix"?
选项
答案
"Helix" is an unrealized mechanical flying machine.
解析
从第一段最后一句可知。
转载请注明原文地址:https://tihaiku.com/zcyy/2873762.html
相关试题推荐
[originaltext]Mrs.RuthLi,aChinesewomanlivinginSingapore,namedher
[originaltext]Mrs.RuthLi,aChinesewomanlivinginSingapore,namedher
TheMid-AutumnFestivalisatraditionalChinesefestivityand______(崇拜月亮的风俗可以
Centuriesago,mandiscoveredthatremovingmoisturefromfoodhelpstopres
Centuriesago,mandiscoveredthatremovingmoisturefromfoodhelpstopres
Centuriesago,mandiscoveredthatremovingmoisturefromfoodhelpstopres
Forcenturiesmendreamedofachievingverticalflight.In400ADChinesech
Forcenturiesmendreamedofachievingverticalflight.In400ADChinesech
Centuriesago,duringtheMiddleAges,mostofthelandinEuropewasowned
Centuriesago,duringtheMiddleAges,mostofthelandinEuropewasowned
随机试题
以下()项是在审计某项计算机应用程序中使用整合测试设施法(ITF)的缺点。A
将2.255002修约为三位有效数字的正确写法是()。A.2.255 B.2
下列与我国四大盆地有关的说法不正确的是:A.柴达木盆地盛产小麦和青稞 B.准噶
民生需求催生新兴职业 【背景链接】 俗话说,“三百六十行,行
美国心理学家华生主张()。 A.遗传决定论 B.环境决定论 C.二因素论
首选用于治疗慢性荨麻疹的药物是A.西替利嗪片 B.氯苯那敏胶囊 C.异丙嗪片
患儿,男,10岁,右足底被铁锈钉刺伤10天,突然出现张口困难,继之出现苦笑面容,
(2016年真题)万盛公司系某省某市一家建筑施工企业。2015年8月,该
银行承兑汇票的承兑银行,应当按照票面金额向出票人收取()的手续费。A:千分之一
(2021年真题第1批)根据《建设工程施工现场环境与卫生标准》,施工单位采取的防
最新回复
(
0
)