首页
登录
职称英语
Someday, in【C1】______ the outer planets of our solar system, humankind wil
Someday, in【C1】______ the outer planets of our solar system, humankind wil
游客
2023-08-30
11
管理
问题
Someday, in【C1】______ the outer planets of our solar system, humankind will want to do【C2】______ send small probes that merely fly rapidly by them. In time, we will want【C3】______ spacecraft that will go【C4】______ orbit around these alien planets, land robots on their moons, and even return rock and soil sample back to Earth.【C5】______ , we will want to send humans to their moons, on at least【C6】______ which liquid water—the fundamental requirementfor life【C7】______ we know it—is believed to be【C8】______ .
For missions such as these, we will need rockets powered by a nuclear reaction【C9】______ igniting chemicals. Chemical rockets have served us well. But the【C10】______ low amount of energy that they can deliver for a given mass of fuel is a severe【C11】______ when dispatching spacecraft【C12】______ long distances. To reach the outer planets, for example, a chemically-powered space vehicle must【C13】______ fuel by having a very small mass and making【C14】______ use of gravity "assists", in which the craft maneuvers close enough to a planet for the planet’s gravity to propel the craft forward,【C15】______ its speed.
In technical term, chemical rockets have low【C16】______ velocity growth, which means that their exhaust velocities are not high enough to【C17】______ very high speed to the rocket. Nuclear rockets,【C18】______ their chemical counterparts, could impart a maximum velocity of【C19】______ about 22 kilometers a second. Such a high velocity would make possible a direct path to Saturn (土星), reducing travel time from about seven years to as【C20】______ as three. [br] 【C8】
选项
A、abundant
B、resourceful
C、valuable
D、considerable
答案
A
解析
形容词辨义题。本处意思是;据信有丰富的液态水存在。故选A abundant“丰富的,充裕的”。
转载请注明原文地址:https://tihaiku.com/zcyy/2969325.html
相关试题推荐
Threeweeksago,theschoolsysteminAlexandria,Va.,announcedthat80%o
Threeweeksago,theschoolsysteminAlexandria,Va.,announcedthat80%o
Theremaybeotherlifeformsintheuniversebecauseover50extrasolarplanets
Theremaybeotherlifeformsintheuniversebecauseover50extrasolarplanets
Theremaybeotherlifeformsintheuniversebecauseover50extrasolarplanets
Theremaybeotherlifeformsintheuniversebecauseover50extrasolarplanets
TheAmericaneconomicsystemisorganizedaroundabasicallyprivateenterpri
Inapurelybiologicalsense,fearbeginswiththebody’ssystemforreactin
Humanity’sprimal(原始的)effortstosystematizetheconceptsofsize,shapes,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
随机试题
[originaltext]Sciencefictionwritershaveoftenimaginedhumanbeingsgoin
[audioFiles]audio_eufm_j49_001(20082)[/audioFiles]A、Theyshouldwaitpatiently.
Thetwogirlslooksomuchalikethatwecanhardly______onefromtheother.A、
Conservationistsmaybemiscalculatingthenumbersofthethreatenedanimals
根据黑体单色辐射的普朗克定律,固体表面的辐射随波长的变化是连续的,因此,任何温度
在下图所示的双链路热备份无线接入网中,STA通过Pontal认证上线,AP当前连
开关柜真空断路器真空灭弧室热图像的δ大于等于()定性为严重缺陷。(A)9
任何人发现有违反本规程的情况,应(),经纠正后才能恢复作业。A.批评教育
设某企业的装卸工月产量最可能估计值为360吨,先进估计值为420吨,保守估计值为
关于财政投资的说法,正确的是()。A.财政投资中包括生产性投资 B.财
最新回复
(
0
)