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
2024-05-05
22
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] 【C5】
选项
A、Eventually
B、Fundamentally
C、Essentially
D、Occasionally
答案
A
解析
副词辨义题。本处意思是:最终,我们要将人也送到这些行星的卫星上去。故选A Eventually“最终”。
转载请注明原文地址:https://tihaiku.com/zcyy/3585586.html
相关试题推荐
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
Americanculturehasbeenenrichedbythevaluesandbeliefsystemsofvirtu
随机试题
Itisquitecommonforaworkingmantomake______forhisoldagebyputtinga
[originaltext]SummermeansinternshipsforthousandsofAmericancollegestu
当专利权人没有规模化实施相关专利的能力或条件时,应优先考虑采用的许可方式是(
可以用于络合滴定 时,络合物的稳定常数应符合( )。A.lgKa>6
共用题干 TheGreatestMysteryofWhalesThe
患者,女性,53岁,休克已10小时,中心静脉压16cmHO(1.57kPa),血
面试热点:守土有责,守土尽责 【热点背景】 1月29日中央指导组派出
幼儿园新购买了一些牛奶糖和水果糖分给小朋友,结果向每个小朋友发2个牛奶糖和3个水
在COSO《内部控制:整合框架》中,没有作为内部控制的目标的是()。A.战略目
为了确保监测系统可靠性,必须做到()。A.系统设计时采取先进实用的方法 B.
最新回复
(
0
)