首页
登录
职称英语
For centuries men dreamed of achieving vertical flight. In 400 A.D. Chinese
For centuries men dreamed of achieving vertical flight. In 400 A.D. Chinese
游客
2024-04-19
40
管理
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 earth as rotation ceased. Leonardo da Vinci con ceive the first mechanical【B1】______,called a "Helix," which could carry man straight up, but was only a design and was never tested.
The ancient-dream was finally realized in 1940 when a Russian engineer piloted a strange look ing craft of steel tubing with a rotating fan【B2】______.It rose awkwardly and verti cally into the air from a standing start,hovered a few feet above the ground,went【B3】______and backwards, and then settled back to earth. The vehicle was called a helicopter.
Imaginations were fired. Men dreamed of going to work in their own personal helicopters. Peo ple anticipated that vertical flight transports would carry millions of passengers as do the airliners of today. Such fantastic expectations were not【B4】______.
The helicopter has now become an extremely useful machine. It【B5】______in military missions, carrying troops, guns and【B6】______ instruments where other air craft cannot go. Corporations use them as airborne offices, many metropolitan areas use them in po lice work, construction and logging companies employ them in various【B7】______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【B8】______crews and supplies. Any urgent mission toa hard-to-get-to placeisa likely task for a helicopter.Among their other【B9】______of use:deliver people across town,fly to and from airports,【B10】______ rescue work, and aid in the search for missing or wanted persons. [br] 【B2】
选项
答案
on top
解析
on top是一个固定表达,表示“在上面”,在这里作方位状语。
转载请注明原文地址:https://tihaiku.com/zcyy/3562043.html
相关试题推荐
[originaltext]Attheturnofthe19thto20thcenturies,theprolificAmeri
[originaltext]Attheturnofthe19thto20thcenturies,theprolificAmeri
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
Forcenturies,farmershaveusedwindmillstopumpwater,crushgrainandpe
随机试题
Americansocietyisnotnap-friendly.Infact,there’sevena【B1】______again
59岁妇女,孕5产4,阴道脱出一物已4年,妇查:宫颈及宫体全部脱出至阴道口外,阴
患者,女性,28岁,因1年来胸闷不适,时有黑矇现象,1周来黑矇现象增多,伴晕厥1
由于湿性黏滞,其致病可出现的症状是( )。A.小腹胀痛 B.下肢水肿 C.
县(市)、区级地方医学会负责组织A.处理医疗事故工作B.首次医疗事故技术鉴定工作
A. B. C. D.
简述幼小衔接工作的主要内容。
某银行2008年初关注类贷款余额为4000亿元,其中在2008年末转为次级类、可
《国务院关于整合城乡居民医疗保险制度的意见》要求整合城镇居民基本医疗保险和新型农
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
最新回复
(
0
)