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
2024-04-20
57
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、Because of its size.
B、Because of its fuel.
C、Because of its complicated engine.
D、Because of its burning time.
答案
B
解析
细节题。文章最后在比较solid—fuel rocket和liquid—fuelrocket的费用高低时,说“But the solid fud,pound per pound,costsabout 10 times as much as the liquid fuel.”固体燃料的价格是液体燃料价格的10倍,也就是说固体燃料火箭运转费用贵是因为其燃料贵,故选B。
转载请注明原文地址:http://tihaiku.com/zcyy/3563060.html
相关试题推荐
[originaltext]W:DidwehaveanyhomeworkassignedforFriday?Ididn’ttakean
[originaltext]W:DidwehaveanyhomeworkassignedforFriday?Ididn’ttakean
[originaltext]Whydowecry?Canyouimaginelifewithouttears?Noton
[originaltext]Whydowecry?Canyouimaginelifewithouttears?Noton
[originaltext](20)Idon’teverwanttotalkaboutbeingawomanscientist
[originaltext]Thegreatadvanceinrockettheory40yearsagoshowedthatl
[originaltext]Thegreatadvanceinrockettheory40yearsagoshowedthatl
[originaltext]Thegreatadvanceinrockettheory40yearsagoshowedthatl
[originaltext]M:Jean,wereyouabletogetthatreportalltypedup?W:Noty
[originaltext]W:Iwanttoregisterforthismathematicscourse.M:I’msorry.
随机试题
Thelatestdiscs,usedforsmallportablecomputers,________3600timesaminute
Itseemstomethattoday’sprime-timeleaderneedsatop-5listthatclearl
[originaltext]Humanbeingshavelivedonthisearthforatleasttwomillion
客房“二进房”操作程序是指( )。A.白天大清扫和晚间夜床服务 B.上午大清
下列关于仲裁协议的说法,错误的有()。A.仲裁协议必须是书面形式 B.当事
二期梅毒的主要表现是( )。A.硬下疳 B.苔癣样变 C.外阴白斑 D.
中枢性瘫痪的特点是( )。A.肌张力降低 B.腱反射减弱 C.浅反射消失
膻中又称作A.气海 B.血海 C.髓海 D.水谷之海 E.经脉之海
能够反映土地价格水平的价格,包括()。A、土地总价格 B、单位地价 C
根据《资源环境承载能力和国土空间开发适宜性评价指南(试行)》,关于本底评价,下列
最新回复
(
0
)