首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Someday, in【C1】______ the outer planets of our solar system, humankind will want to do【C2】______ send small probes that merely
Someday, in【C1】______ the outer planets of our solar system, humankind will want to do【C2】______ send small probes that merely
admin
2013-06-02
36
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.
【C15】
选项
A、slowing
B、decreasing
C、boosting
D、simulating
答案
C
解析
动宾搭配题。本处意思是:以利用该行星的引力来拉动飞船前行,提高速度。故选C boosting“提高”。
转载请注明原文地址:https://kaotiyun.com/show/B2n7777K
0
大学英语六级
相关试题推荐
ThisyearthecombinedadvertisingrevenuesofGoogleandYahoo!willrivalthecombinedprimetimeadrevenuesofAmerica’sthre
Afterseveralyears’practice,wearegladtoseethat______(义务教育已经进入了一个崭新的阶段).
TheAmericanideaofrespectinghumanrightscamefromseveralsources.First,thecolonistshadbeen【36】oftheirfightsinthe
TheAmericanideaofrespectinghumanrightscamefromseveralsources.First,thecolonistshadbeen【36】oftheirfightsinthe
A、Itisthelargestcityintheworld.B、Ithasmanyculturalandamusementplaces.C、Ithasthemostbeautifulscenery.D、Itha
Scotlandisauniqueplace.IthassomeofthemostbeautifulcitiesinEurope,alivingevidenceofasplendidandproudpast.
Largecompaniesneedawaytoreachthesavingsofthepublicatlarge.Thesameproblem,onasmalle【B1】______facespracticall
Largecompaniesneedawaytoreachthesavingsofthepublicatlarge.Thesameproblem,onasmalle【B1】______facespracticall
Largecompaniesneedawaytoreachthesavingsofthepublicatlarge.Thesameproblem,onasmalle【B1】______facespracticall
A、Onlyone.B、Two.C、Three.D、Morethanthree.A
随机试题
未被椎前筋膜覆盖的是()
在通信网中,传输链路是网路节点的连接媒介,是信息和信号的传输通路。()
A.皮质醇B.皮质酮C.醛固酮D.脱氧皮质酮E.脱氢表雄酮肾上腺皮质束状带细胞分泌
最可能的诊断是( )。在住院行手术治疗前,应常规进行下列哪项检查( )。
某截瘫病人,入院时骶尾部压疮,面积2.5cm×2cm,深达肌层,创面有脓性分泌物,周围有黑色坏死组织。护理措施是
赵老师板书时写了一个错字,王亮站起来大声说:“老师,字写错了。”赵老师不高兴地说:“多什么嘴,你是老师,我是老师?坐下!”王亮默默地坐下了,自此,再也没有学生敢指出老师的错误了,对赵老师的做法正确的评价是()。
下列选项中,都与巾国古代科举考试有关的一组词语是:
根据以下资料,回答问题。2005年中国网络广告市场中,份额最大的类型是:
The______flowerswereallthatremained.
Whatconclusioncanbedrawnfromthescientists’observation?
最新回复
(
0
)