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
2023-08-22
67
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".(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://tihaiku.com/zcyy/2946795.html
相关试题推荐
[originaltext]I’dliketosharewithyoutodaymyexperiencewithanewapp
[originaltext]Theflag,themostcommonsymbolofanationinthemodernwo
[originaltext]Theflag,themostcommonsymbolofanationinthemodernwo
[originaltext]W:DepartmentofArt,DesignandMedia.CanIhelpyou?M:Yes.I
[originaltext]W:DepartmentofArt,DesignandMedia.CanIhelpyou?M:Yes.I
[originaltext]W:DepartmentofArt,DesignandMedia.CanIhelpyou?M:Yes.I
[originaltext]W:DepartmentofArt,DesignandMedia.CanIhelpyou?M:Yes.I
[originaltext]M:Nextmonthyou’regoingtocelebrateThanksgivingDay.Whenis
[originaltext]M:Nextmonthyou’regoingtocelebrateThanksgivingDay.Whenis
[originaltext]W:I’msorry,Mike.Ihavetoputoffourmeetingtillfouro’clo
随机试题
Afive-year-oldboycanspeaktwoforeignlanguages,______surprisesallthepe
Georgehasabigcoffee______onthefrontofhisjacket.(1994年考试真题)A、spotB、mar
Oneofthereasonstropicalforestsarebeingcutdownsorapidlyisdemand
A.用这些数字1-7对塑料进行分类,可以帮助我们科学地使用塑料制品,同时也有利于
以下场所中采光系数标准值不属于强制执行的是:A.住宅起居室 B.普通教室 C
患者,男性,16岁,因右下肢肌肉血肿,关节腔出血,两天入院,以往有多次发作史,家
()交通主管部门负责组织领导本行政区域的道路运输管理工作。A.县级以上地方人民政
《隔离开关分合闸位置“双确认”改造技术规范》中一体化数字摄像机应支持()配置文
变电基建工程验收中,关键点见证应当形成记录,交()或物资部门督促整改。项目管
下列监理单位的质量责任和义务说法错误的是()。A.与被监理工程的施工承包单位以
最新回复
(
0
)