首页
登录
职称英语
[originaltext] The great advance in rocket theory 40 years ago showed that l
[originaltext] The great advance in rocket theory 40 years ago showed that l
游客
2023-09-03
64
管理
问题
The great advance in rocket theory 40 years ago showed that liquid-fuel rackets 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 a bout as powerful as powerful 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 as 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 bunting of the rocket engine can be stopped completely; it can be reignited when desired. A solid-fuel rocket, tin 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 a very short notice. A liquid fuel rocket has to be fueled flint and Carl not be held in readiness in very long slier it has been fueled. However, once a solid-fuel rocket has been ignited, it will keep burning. It can’t be stopped and reignited whenever desired. Because a solid fuel rocket can be kept ready for a long time, most missiles employ solid fuels, but manned space flight needs the line adjustments that can only be pro vided by liquid-fuel rocket. It may be added that a liquid-fuel rocket is an expensive device; a large solid-fund rocket is, by comparison cheap.
选项
A、Because of its size.
B、Because of its fuel.
C、Because of its complicated engine.
D、Because of its burning time.
答案
D
解析
Why are the solid-fuel rockets expensive to operate?
转载请注明原文地址:https://tihaiku.com/zcyy/2980903.html
相关试题推荐
[originaltext]DuringtheChristmasshoppingrushinLondon,aninteresting
[originaltext]W:Hi,ProfessorHiggins.M:Hi,Julia.W:Wouldyoubeabletoh
[originaltext]M:Idon’tenjoydatinganymore,Ican’tseemtofindanyoneIha
[originaltext]M:Idon’tenjoydatinganymore,Ican’tseemtofindanyoneIha
[originaltext]M:DoyourememberthefilmonspaceexplorationthatwasonTVl
[originaltext]M:DoyourememberthefilmonspaceexplorationthatwasonTVl
[originaltext]M:DoyourememberthefilmonspaceexplorationthatwasonTVl
[originaltext]M:DoyourememberthefilmonspaceexplorationthatwasonTVl
[originaltext]M:DoyourememberthefilmonspaceexplorationthatwasonTVl
[originaltext]M:DoyourememberthefilmonspaceexplorationthatwasonTVl
随机试题
Firstofcourse,itisplainthatintheyear2010everyonewillhaveathis
[originaltext]M:YouknowIwillbethemaintalkerintheclassroomdiscussion
Inalittle-knownpartofthecounter-terrorismworld,oneofthemosteff
[originaltext]Awaiterhasreturnedacheckworthnearly$424,000totheretire
根据《中华人民共和国民法典》,我国诉讼时效最长为()年。A.15 B.10
如右图,在梯形ABCD中,点E、F分别是腰AB、CD上的点. (1)证明:如
下列()为水利水电工程施工现场一类负荷。A、基坑内的排水施工 B、混凝上浇筑施
根据标准临街宗地单价求得一宗临街深度为50m、临街宽度为20m的土地总价为280
投资项目决策分析与评价的基本要求包括贯彻落实科学发展观、资料数据准确可靠和()
使慢性粒细胞白血病达到血液学缓解首选的治疗是( )。A.应用全反式维A酸 B
最新回复
(
0
)