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
23
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:https://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
Thesciencebehindsolar(太阳的)energyisnotnew.ButSheridanCommunityScho
大数据时代的安全与传统安全相比,变得更加简单。
土工织物渗透性试验的水温必须恒定在20℃。
教师作为独立的职业,是人类社会发展到一定阶段的产物,它的产生要求以下条件A.人
有关晕针的处理方法,叙述不正确的是A.立即停止针刺,将针全部起出 B.宽衣解带
变压器出现()、外部过电压、系统谐振等异常状况后,应检查中性点电容隔直/电阻
过程旨在结果,结果通过过程取得,并为过程的改进和创新提供()。 A.目标B
下列关于易燃液体分类的叙述中,错误的是()。A.闪点<28℃的液体为甲类火险物
中国人民抗日军事政治大学是中国共产党领导下创立和发展起来的一所干部学校,创立初期
北创公司是一家白酒生产企业。为了进一步提高产品质量,北创公司通过图表形式将白酒生
最新回复
(
0
)