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
Black Holes Most scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe
Black Holes Most scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe
admin
2009-01-21
53
问题
Black Holes
Most scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere (球体). Astronomers (天文学家)think that at the center of a black hole there is a single point in space with infinite (无限的)density (稠密). This single point is called a singularity (奇点). If the singularity theory is correct, it means that when a massive star collapses, all the material in it disappears into the singularity. The center of a black hole would not really be a hole at all, but an infinitely dense point. Anything that crosses the black hole is pulled in by its great gravity.
Although black holes do exist, they are difficult to observe. These are the reasons.
-- No light or anything else comes out of black holes. As a result, they are invisible to a telescope.
-- In astronomical terms, black holes are truly. For example, a black hole formed by the collapse of a giant star would have an event horizon(视界)only 18 miles across.
-- The nearest black holes would be dozens of light years away from Earth. One light year is about 6 trillion(万亿)miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.
In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found, however, so black holes remain one of the mysteries of the universe.
选项
A、Right
B、Wrong
C、Not mentioned
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/tjQd777K
本试题收录于:
职称英语理工类B级题库职称英语分类
0
职称英语理工类B级
职称英语
相关试题推荐
HappyMarriage,HappyHeartHappilymarriedpeoplehavelowerbloodpressure【51】______unhappilymarriedpeopleorsingles,
Intherecentpast,medicalresearchershaveshownthatheartdiseaseisassociatedwithcertainfactorsinourday-to-daylives
ActiveinOldAgeKeepsPeopleMobilePeopleover70whoaren’tactivearemorelikelytodevelopproblemswalkingorclimbin
Organicfood:Why?1.Europeisnowthebiggestmarketfororganicfoodintheworld,expandingby25percentayearoverth
ExercisingYourMemory1Agingdoesnotmeanadramaticdeclineinmemorypower,unlessyouhelpithappenbylettingyourmind
Hersisterurgedhertoapplyforthejob.
HealthEducation1Healtheducationisthepartofhealthcarethatisconcernedwithpromotinghealthybehavior.Aperson’sbeh
Wewereastonishedtohearthattheirfootballteamhadwonthechampion.
There’snofuninspendingthewholeeveningplayingcards.
WideWorldofRobotsEngineerswhobuildandprogramrobotshavefascinatingjobs.Theseresearcherstinker(修补)withmachines
随机试题
精神病患者的幻觉症也是一种白日梦。那么,它同科学家、艺术家和哲学家的白日梦有何不同呢?区别之一是:前者是个不可逆过程,后者是可逆过程。科学家、艺术家和哲学家的创作是从现实世界出发最后又能落脚到现实世界。当舒曼的《梦幻曲》一回到现实,萦绕在千万人的心坎,人们
z=x3f(),其中f为可微函数,证明=3z.
全球医院发展创新建设的方向是
患者,男,50岁。患萎缩性胃炎15年,并发巨细胞性贫血。其贫血发生机制,是因为缺乏
诊脉时,用指目沿脉道的轴向上下指指相移,以体会脉动应指范围的长短和脉搏来势的虚实,为诊脉时,将指目对准脉脊后,顺应脉搏的动势,左右内外微微推动,以进一步体会脉率快慢,了解脉搏的力量和趋势,为
关于宪法规范,下列哪一说法是不正确的?
下列关于基金托管人的信息披露义务的说法,不正确的是()。
古人云“苟利国家生死以,岂因祸福避趋之”、“报国之心,死而后已”。集中体现的爱国主义情怀是()
一种资产在未来的支付事先是未知,这样的资产称为风险资产.设一种风险资产未来的支付为X,它的取值依赖于未来的自然状态,设未来所有可能的自然状态为Ω={ω1,ω2,ω3,ω4,ω5},X对状态的依赖关系如下:在未来,观察X的取值能够确定是否发生的事件有哪
A、Bookdinnerforthewholefamilyatarestaurant.B、Prepareamealaloneforthefamily.C、Cookmeatforthefamily.D、Helpth
最新回复
(
0
)