首页
登录
职称英语
The great advance in rocket theory 40 years ago showed that liquid-fuel rocke
The great advance in rocket theory 40 years ago showed that liquid-fuel rocke
游客
2025-05-10
7
管理
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". The question is meaningless; one might as well ask whether a gasoline or a diesel engine is "better". It all depends on the purpose. 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 re-ignited 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 re-ignited whenever desired (it could conceivably be stopped and re-ignited 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, but manned space flight needs the fine adjustments that can only be provided by liquid fuels. It may be added that a liquid-fuel rocket is an expensive device; a large solid-fuel rocket is, by comparison, cheap. But the solid fuel, pound per pound; costs about 10 times as much as the liquid fuel. So you have, on the one, hand, an expensive rocket with a cheep fuel and on the other hand a comparatively cheap rocket with an expensive fuel. [br] The author feels that a comparison of liquid and solid-fuel rockets shows that ______.
选项
A、neither type is very economical
B、the liquid-fuel rocket is best
C、each type has certain advantages
D、the solid-fuel rocket is hest
答案
C
解析
文中提到一些外行可能会问,相较而言liquid and solid-fuel rockets哪个更好,作者对此问题的看法是The question is meaningless,接着在文中分别阐述了两种类型火箭各自的优缺点,可以判断选项C符合。
转载请注明原文地址:https://tihaiku.com/zcyy/4069690.html
相关试题推荐
Advancementinthearmyisoftengiventothepersonwho______.A、callsattentio
Initsbroadestsense,attributiontheoryisconcernedwithhowordinarypeople
Thegreatadvanceinrockettheory40yearsagoshowedthatliquid-fuelrocke
Thegreatadvanceinrockettheory40yearsagoshowedthatliquid-fuelrocke
Perhapsallsocieties(aresignificantlymoreadvanced)thanourownhaveachiev
Oneoutcomeoftherapidadvanceoftechnologyisthebreakdownofthetradition
Thecarpollutes,butadvancesinfuelqualityandefficiency,andinmicropro-c
Dr.Thompsongaveanexpositionofthetheoryandpracticeofsocialism.A、accoun
Ourtheoryandpracticeintheareaofsentencinghaveundergoneagradualb
Ourtheoryandpracticeintheareaofsentencinghaveundergoneagradualb
随机试题
Executivecoachingisprimarilyconcernedwithconfidentialone-to-onediscu
Demographyisthestatisticalstudyofhumanpopulations.Itcanbeagen
甲单位为中央级事业单位,按要求执行中央级事业单位的各项规定,2021年3月,甲单
可燃性构件是指用可燃材料做成的构件,以下构件中()不属于可燃性构件。A.木柱
为提纯下列物质(括号中为杂质),所选除杂试剂和分离方法错误的是()。 A.
下列装置应用于实验室制氯气并回收氯化锰的实验,能达到实验目的的是( )。
根据一节课所完成任务的类型数,可分为() A、单一课与综合课 B、新授课与
根据有关规定,110报警服务平台负责受理群众报警、求助、投诉,下列属于报警类警情
甲、乙两个单位人数相同,甲单位的党员占总人数的20%,乙单位的党员占总人数的25
奥肯定律描述的是()。A.经济波动和就业 B.经济增长和通货膨胀 C.经济
最新回复
(
0
)