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
19
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] 【C13】
选项
A、conserve
B、consume
C、exploit
D、contain
答案
A
解析
动词辨义题。本处意思是:…以化学燃料为动力的宇宙飞船不得不保存很少的燃料。故选A conserve“保存”。
转载请注明原文地址:https://tihaiku.com/zcyy/2969330.html
相关试题推荐
TheAmericaneconomicsystemisorganizedaroundabasicallyprivateenterpri
Humanity’sprimal(原始的)effortstosystematizetheconceptsofsize,shapes,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
TheUnitedStatescourtsystem,aspartofthefederalsystemofgovernment,
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
随机试题
Therewas_____onthemenuyesterday.A、somethingofalambB、alambC、lambD、th
约翰.格利和爱德华.肖在20世纪50年代提出了( ),揭示了金融与实体经济之间
A.肾阴虚证 B.肾阳虚证 C.胃阴虚证 D.胃热熏蒸证 E.阴虚火旺证
A.肾小球肾炎 B.遗传性血管神经性水肿 C.严重感染 D.CIC清除障碍
油浸变压器排油注氮灭火装置质量评价细则中,下列情况应认定为D级的是:()
2012年,浙江省工商服务类社会团体的数量约占社会组织数量的:() A.8
某公司是甲省乙市的市属重要国有独资公司,为扩展业务,该公司决定与甲省乙市另一家公
下列属于城市总体规划强制性内容的是( )。A.用水量标准 B.城市防洪标准
分部分项工程量清单的项目特征应按“清单计价规范”附录中规定的项目特征,结合(
医疗机构发现发生或者可能发生传染病暴发流行时,应当A.在2小时内向所在地县级人民
最新回复
(
0
)