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、Neither of the two types of rockets is very economical. B、The liquid-fuel rocket is best. C、Each type of rocket has certain ad
A、Neither of the two types of rockets is very economical. B、The liquid-fuel rocket is best. C、Each type of rocket has certain ad
admin
2015-04-30
29
问题
The great advance in rocket theory 40 years ago showed that liquid-fuel rockets were far superior in every respect to the skyrocket with its weak solid fuel, the only kind of rocket then known. However, during the last decade, large solid-fuel rockets with solid fuels about as powerful as liquid fuels have made their appearance, and it is a favorite layman’s question to inquire which one is "better".(16)The question is meaningless; one might as weft" ask whether a gasoline or a diesel engine is "better". It all depends on the purpose.(18)/(19)A liquid fuel rocket is complicated, but has the advantage that it can be controlled beautifully. The burning of the rocket engine can be stopped completely; it can be reignited when desired. In addition, the thrust can be made to vary by adjusting the speed of the fuel pumps. A solid-fuel rocket, on the other hand, is rather simple in construction, though hard to build when a really large size is desired. But once you have a solid-fuel rocket, it is ready for action at very short notice. A liquid-fuel rocket has to be fueled first and cannot be held in readiness for very long after it has been fueled. However, once a solid-fuel rocket has been ignited, it will keep burning. It cannot be stopped and reignited whenever desired(it could conceivably be stopped and reignited after a pre-calculated time of burning has elapsed)and its thrust cannot be varied. Because a solid-fuel rocket can be kept ready for a long time, most military missiles employ solid fuels,(18)but manned spaceflight needs the fine adjustments that can only be provided by liquid fuels.(19)It may be added that a liquid-fuel rocket is an expensive device; a large solid-fuel rocket is, by comparison, cheap.(17)/(19)But the solid fuel, pound per pound, costs about 10 times as much as the liquid fuel.(19)So you have, on the one hand, an expensive rocket with a cheap fuel and on the other hand a comparatively cheap rocket with an expensive fuel.
Questions 16 to 19 are based on the passage you have just heard.
16. What conclusion can we draw from the passage?
17. Why are the solid-fuel rockets expensive to operate?
18. What’s the most important consideration for the rocket that used for manned spaceflight?
19. Which of the following statements is NOT the characteristic of liquid-fuel rockets?
选项
A、Neither of the two types of rockets is very economical.
B、The liquid-fuel rocket is best.
C、Each type of rocket has certain advantages.
D、The solid-fuel rocket is best.
答案
C
解析
推理题。文中提到两种火箭的优劣时说“The question ismeaningless.It all depends on the purpose”显然两种火箭都有其长处。故选C。
转载请注明原文地址:https://jikaoti.com/ti/lZ6FFFFM
0
大学英语六级
相关试题推荐
A、Haveanexam.B、Double-checktheanswers.C、Correctthetestscoreimmediately.D、Markthewronganswer.B对话中男士说他觉得有一个答案被判错了,女
A、1ton.B、2.5tons.C、8tons.D、33tons.A选项的内容表明,本题考查与重量相关的信息。短文中提到,2005年之前,在西非缴获的可卡因总量为1吨,故答案为A)。
A、About25%.B、About15%.C、About20%.D、About50%.C选项的内容表明,本题考查百分比,听音时应留意相关的信息。短文中提到,研究发现每五个美国成年人中就有一个人吸烟,由此可推断,美国大约有20%的成年人吸烟
HowSafeIsYourMobilePhone?[A]IttakesalittleextraworktogetintouchwithAndreaBoland.TheMainestaterepresentativ
A、Bysendinge-mailstootheruniversities.B、Bytypingtherequestinthecomputer.C、Byturningtothelibrarianforadvice.D
A、Manyuniversitieshavecommonproblems.B、Mostcollegestudentscan’tadaptthemselvestothem.C、Theconditionscan’tbeimpr
A、Authority.B、Independence.C、Goodluck.D、Agoodrelationship.B短文中提到,WhatIreallywantistobemoreindependentthatIamn
A、Thevalueofknowinghumanhistory.B、Theimportanceofsharinginformation.C、Howtobringbackthreatenedlanguages.D、Whye
Apunctualpersonisinthehabitofdoingeverythingatthepropertimeandisneverlateinkeepinganappointment.Theunpunc
Attheendofhistwotermsinoffice,RonaldReaganviewedwithsatisfactiontheachievementsofhisinnovativeprogramknowna
随机试题
毛泽东思想活的灵魂是()。
江城大学批转教务处的报告,行文应选用的文种()
A、吞咽困难B、声嘶C、两者均可D、两者均不可食管癌早期可见
下列不是人工流产漏吸原因的是
A.阻塞性肺不张B.肺实变C.胸腔积液D.胸膜肥厚(轻度)E.肺气肿查体发现气管居中,患侧触觉语颤增强,可闻及支气管呼吸音的情况提示
卡环体的作用是
患者体内有VitB12辅助因子的抗体,此抗体可使肠道VitB12吸收障碍,该种贫血属于
总代理
希望和他人订立合同的意思表示称为()。
已知2016年经营资产增加1000万元,经营负债增加200万元,留存收益增加400万元,销售收入增加2000万元,则2016年外部融资销售增长比为()。
最新回复
(
0
)