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
Choose the most suitable headings for paragraphs B-Efrom the list of headings below. Write the appropriate numbers i-ix in boxes
Choose the most suitable headings for paragraphs B-Efrom the list of headings below. Write the appropriate numbers i-ix in boxes
admin
2014-05-25
87
问题
Choose the most suitable headings for paragraphs B-Efrom the list of headings below.
Write the appropriate numbers i-ix in boxes 1-4 on your answer sheet.
List of Headings
i How the reaction principle works
ii The impact of the reaction principle
iii Writers’ theories of the reaction principle
iv Undeveloped for centuries
v The first rockets
vi The first use of steam
vii Rockets for military use
viii Developments of fire
ix What’s next?
THE ROCKET - FROM EAST TO WEST
A The concept of the rocket, or rather the mechanism behind the idea of propelling an object into the air, has been around for well over two thousand years. However, it wasn’t until the discovery of the reaction principle, which was the key to space travel and so represents one of the great milestones in the history of scientific thought, that rocket technology was able to develop. Not only did it solve a problem that had intrigued man for ages, but, more importantly, it literally opened the door to exploration of the universe.
B An intellectual breakthrough, brilliant though it may be, does not automatically ensure that the transition is made from theory to practice. Despite the fact that rockets had been used sporadically for several hundred years, they remained a relatively minor artefact of civilisation until the twentieth century. Prodigious efforts, accelerated during two world wars, were required before the technology of primitive rocketry could be translated into the reality of sophisticated astronauts. It is strange that the rocket was generally ignored by writers of fiction to transport their heroes to mysterious realms beyond the Earth, even though it had been commonly used in fireworks displays in China since the thirteenth century. The reason is that nobody associated the reaction principle with the idea of travelling through space to a neighbouring world.
C A simple analogy can help us to understand how a rocket operates. It is much like a machine gun mounted on the rear of a boat. In reaction to the backward discharge of bullets, the gun, and hence the boat, move forwards. A rocket motor’s ’bullets’ are minute, high-speed particles produced by burning propellants in a suitable chamber. The reaction to the ejection of these small particles causes the rocket to move forwards. There is evidence that the reaction principle was applied practically well before the rocket was invented. In his Noctes Atticae or Greek Nights, Aulus Gellius describes ’the pigeon of Archytas’, an invention dating back to about 360 BC. Cylindrical in shape, made of wood, and hanging from string, it was moved to and fro by steam blowing out from small exhaust ports at either end. The reaction to the discharging steam provided the bird with motive power.
D The invention of rockets is linked inextricably with the invention of ’black powder’. Most historians of technology credit the Chinese with its discovery. They base their belief on studies of Chinese writings or on the notebooks of early Europeans who settled in or made long visits to China to study its history and civilisation. It is probable that, some time in the tenth century, black powder was first compounded from its basic ingredients of saltpetre, charcoal and sulphur. But this does not mean that it was Immediately used to propel rockets. By the thirteenth century, powder-propelled fire arrows had become rather common. The Chinese relied on this type of technological development to produce incendiary projectiles of many sorts, explosive grenades and possibly cannons to repel their enemies. One such weapon was the ’basket of fire’ or, as directly translated from Chinese, the ’arrows like flying leopards’. The 0.7 metre-long arrows, each with a long tube of gunpowder attached near the point of each arrow, could be fired from a long, octagonal-shaped basket at the same time and had a range of 400 paces. Another weapon was the ’arrow as a flying sabre’, which could be fired from crossbows. The rocket, placed in a similar position to other rocket-propelled arrows, was designed to increase the range. A small iron weight was attached to the 1.5m bamboo shaft, just below the feathers, to increase the arrow’s stability by moving the centre of gravity to a position below the rocket. At a similar time, the Arabs had developed the ’egg which moves and burns’. This ’egg’ was apparently full of gunpowder and stabilised by a 1.5m tail. It was fired using two rockets attached to either side of this tail.
E It was not until the eighteenth century that Europe became seriously interested in the possibilities of using the rocket itself as a weapon of war and not just to propel other weapons. Prior to this, rockets were used only in pyrotechnic displays. The incentive for the more aggressive use of rockets came not from within the European continent but from far-away India, whose leaders had built up a corps of rocketeers and used rockets successfully against the British in the late eighteenth century. The Indian rockets used against the British were described by a British Captain serving in India as ’an iron envelope about 200 millimetres long and 40 millimetres in diameter with sharp points at the top and a 3m-long bamboo guiding stick’. In the early nineteenth century the British began to experiment with incendiary barrage rockets. The British rocket differed from the Indian version in that it was completely encased in a stout, iron cylinder, terminating in a conical head, measuring one metre in diameter and having a stick almost five metres long and constructed in such a way that it could be firmly attached to the body of the rocket. The Americans developed a rocket, complete with its own launcher, to use against the Mexicans in the mid-nineteenth century. A long cylindrical tube was propped up by two sticks and fastened to the top of the launcher, thereby allowing the rockets to be inserted and lit from the other end. However, the results were sometimes not that impressive as the behaviour of the rockets in flight was less than predictable.
F Since then, there have been huge developments in rocket technology, often with devastating results in the forum of war. Nevertheless, the modern day space programs owe their success to the humble beginnings of those in previous centuries who developed the foundations of the reaction principle. Who knows what it will be like in the future?
The greatest outcome of the discovery of the reaction principle was that
选项
A、rockets could be propelled into the air.
B、space travel became a reality.
C、a major problem had been solved.
D、bigger rockets were able to be built.
答案
B // space travel became a reality
解析
转载请注明原文地址:https://kaotiyun.com/show/3FNO777K
本试题收录于:
雅思阅读题库雅思(IELTS)分类
0
雅思阅读
雅思(IELTS)
相关试题推荐
Thefunction/hasthepropertythatf(x)=f(x+1)forallnumbersx.Iff(4)=17,whatisthevalueoff(8)?
Thefigureaboveshowsthegraphofthefunction/definedbyf(x)=\2x\+4forallnumbersx.Forwhichofthefollowingfunctio
Ifthefunctiongisdefinedforallnonzeronumbersybyg(y)=,findthevalueofeachofthefollowing.(a)g(2)(b)g(-2)(c)g
Inaboxof10electricalparts,2aredefective.(a)Ifyouchooseonepartatrandomfromthebox,whatistheprobabilitythat
Whichoftheintegers2,9,19,29,30,37,45,49,51,83,90,and91areprimenumbers?
Fromasetof100numbers,halfwereselectedtoformgroupI,and60percentoftheremainingnumberswereselectedtoformgro
Thesumofnnumbersisgreaterthan48.Iftheaverage(arithmeticmean)ofthennumbersis1.2,whatistheleastpossibleva
随机试题
X6132型铣床的丝杠螺母间的轴向间隙通过___________调整。
功似龙骨而长于软坚散结的药物是
患者,男性,68岁,有慢性阻塞性肺气肿病史。咳嗽、脓痰伴气急加重2周,今晨神志恍惚,体检:嗜睡,口唇发绀,两肺湿啰音,心率116次/分,血压185/105mmHg。最可能的诊断是
A.胰岛素静脉注射B.刺激胰岛B细胞释放胰岛素C.胰岛素皮下注射D.甲苯磺丁脲E.增加肌肉组织中糖的无氧酵解胰岛素依赖型重症糖尿病用
某企业经批准于2000年6月取得了市郊一幅30亩面积的国有土地使用权,领取了土地使用证,但由于一直未能筹措到足够的投资资金,原拟投资的项目至2002年10月仍未能开工,该幅土地也一直未予使用,且未经原批准机关同意。对此,正确的处理方法应是下列哪种方法___
不开槽管道施工,当周围环境要求控制地层变形或无降水条件时,宜采用()。
自理报关企业必须是具有进出口经营权的单位,具体包括______。
A注册会计师负责审计公司2010年度财务报表。在针对销售费用的发生认定实施细节测试时,A注册会计师决定采用传统变量抽样方法实施统计抽样,相关事项如下:(1)A注册会计师抽样单元界定为销售费用总额中的每个货币单元。(2)A注册会计师将总体分成两层,使每层
存款人开立的账户除办理存款人本身的业务,还可以出租和转让账户。()
在语言系统中,精确和模糊是两个相互矛盾的特征,然而,它们却对人们交流的有效性和可靠性起着重要的作用。只有一种语言是完全精确的,它才是完全有效的。如果一种语言是完全精确的,那么其基本音节的每一种可能的组合都将成为一个有独立意义的词。但是,如果人类的听觉器官接
最新回复
(
0
)