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、The inexpensive cost of construction. B、The capacity of lifting heavy spacecraft into orbit. C、The easy control performance. D
A、The inexpensive cost of construction. B、The capacity of lifting heavy spacecraft into orbit. C、The easy control performance. D
admin
2015-04-30
53
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、The inexpensive cost of construction.
B、The capacity of lifting heavy spacecraft into orbit.
C、The easy control performance.
D、The inexpensive cost of operation.
答案
C
解析
推理题。题目是问用于发射人造航天器的火箭要重点考虑什么。短文中在提到manned spaceflight时说要使用液体燃料火箭,根据前文,比较液体燃料火箭和固体燃料火箭的优缺点时说到,液体燃料火箭的优点是能够被完美地控制,其点火装置可以完全停止,在需要的时候可以重新点火,此外,其助推器可以通过调整燃油泵的速度进行改变。所以液体燃料火箭有易于控制的特点,故选C。
转载请注明原文地址:https://kaotiyun.com/show/AsQ7777K
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、Adrivingtest.B、Apolicemovie.C、Atrafficaccident.D、Thewaytomakesignals.C由对话中女士提到的lookatthemessyou’vemadeofm
BringOurSchoolsoutofthe20thCentury[A]There’sadarklittlejokeexchangedbyeducatorswithanopposingtrace:RipVanW
BringOurSchoolsoutofthe20thCentury[A]There’sadarklittlejokeexchangedbyeducatorswithanopposingtrace:RipVanW
A、Becauseitislesslikelytorunaway.B、Becauseitislesslikelytobetooshywithotherdogs.C、Becauseit’seasierforit
A、Shehastochangethetimeforthetrip.B、Shehasn’tdecidedwheretogonextmonth.C、Shecan’taffordthetimeforthetrip
Alcoholhasapeculiarrelationshiptohappiness.Wedrinktocelebrate,butbecausealcoholworksasadepressant,itendsupd
Today,moreandmorepeopleintheUnitedStatesareusingcreditcardsinsteadofmoneytobuythethingstheyneed.Almostany
Today,moreandmorepeopleintheUnitedStatesareusingcreditcardsinsteadofmoneytobuythethingstheyneed.Almostany
Ofallthe【C1】______ofagoodnight’ssleep,dreamsseemtobeleastwithinourcontrol.Indreams,awindowopensintoaworld
随机试题
心身疾病治疗原则不包括
依据《职业病防治法》的规定,职业病危害控制效果的评价工作由依法设立的取得()以上人民政府卫生行政部门资质认证的职业卫生技术服务机构进行。
下列关于疏散出口检查内容的叙述中,错误的是()。
根据有关规定,中外合资经营企业的外国投资者出资比例低于注册资本25%的,下列表述正确的是()。
共同配送就是指在一定的区域内,为使物流合理化,对有若干个定期需求的货主,共同要求某一个卡车运输企业,利用同一个运输系统完成的配送。()
布置家庭作业对心理咨询的作用是()。
________指个人认知结构在内容和组织方面的特征,它主要包括认知结构中适当的起固定作用的观念的可利用性、可辨别性及稳定性和清晰性三个变量。
经过二百多年、几易其主的老房子,原先的一切早已空空如也。历史在哪里呢?我细心留意便注意到,它圆厅独有的凸形窗玻璃得到刻意的保护,仅存的壁炉、座钟与吊灯被视为珍宝,地窖里的宗教壁画如同刚被考古发现一般原封未动。一切修补都采用原先的形制、材质与制作方法。历史不
在考生文件夹下,“samp1.accdb”数据库文件中已建立三个关联表对象(名为“线路”、“游客”和“团队”)和窗体对象“brow”。试按以下要求,完成表和窗体的各种操作:建立“线路”和“团队”两表之间的关系并实施参照完整。
Usually,inanattackofinfluenza,thepatient’slimbsache.
最新回复
(
0
)