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
How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets,and thousands of spar
How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets,and thousands of spar
admin
2015-01-09
29
问题
How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets,and thousands of sparkling stars.
You can see even more with a telescope. You might see stars where before you only saw dark space. You might see that many stars look larger than others. You might see that some stars that look white are really red or blue. With bigger and bigger telescopes you can see more and more objects in the sky. And you can see those objects in more and more details.
But scientists believe there are some things in the sky that we will never see. We won’t see them with the biggest telescope in the world, on the clearest night of the year. That’s because they’re invisible. They’re the mysterious dead stars called black holes.
You might find it hard to imagine that stars die. After all,our Sun is a star. Year after year we see it up in the sky burning brightly,giving us heat and light. The Sun certainly doesn’t seem to be getting old or weak. But stars do burn out and die after billions of years.
As a star’s gases burn,they give off light and heat. But when the gas runs out,the star stops burning and begins to die.
As the star cools,the outer layers of the star pull in toward the center. The star squashes into a smaller and smaller ball. If the star was very small, the star ends up as a cold, dark ball called a black dwarf. If the star was very big.it keeps squashing inward until it’s packed together tighter than anything in the universe.
Imagine if the each were crushed until it was the size of a tiny marble. That’s how tightly this dead star, a black hole is packed. What pulls the star in toward its center with such power? It’s the same force that pulls you down when you jump—the force called gravity. A black hole is so tightly packed that its gravity sucks in everything—even light. The light from black hole can never come back to your eyes. That’s why you see nothing but blackness.
So the next time you stare up at the night sky,remember: there’s more in the sky than meets the eyes! Scattered in the silent darkness are black holes—the great mystery of space.
Why can’t you see light when you look at a black hole?
选项
A、Because most black holes are so far away.
B、Because the gravity of a black hole is so strong that it sucks the light inward.
C、Because as the star’s gases burn.it stops giving off heat and light.
D、Because as a star cools, its outer layers pull in toward its center.
答案
B
解析
题目问:当你看到一个黑洞时,为什么你不能见到光?倒数第二段“A black hole is so tightly packedthat its gravity sucks in everythIng——even light.The light from black hole Can never come back to youreyes.That’s why you see noting but blackness.”通过这段话可知,黑洞是如此的紧凑,以至于它的重力吸收一切东西。甚至是光。黑洞里的光永远也到不了你的眼睛里。这就是你为什么看到一片漆黑的原因。所以,答案是A。
转载请注明原文地址:https://kaotiyun.com/show/iBLO777K
0
考博英语
相关试题推荐
CultureingeneralAisconcernedwithbeliefsandvaluesBonthebasisofthatpeopleinterpretexperiencesandbehave,individu
Onereasonpeoplebelievephysician-assistedsuicideshouldbeavailableforthosewhorequestit,isthatpeoplefeartheloss
IntheAmericanfamily,thehusbandandwifeusuallyshareimportantdecisionmaking.Whenthechildrenareoldenough,theytak
Ifitwereonlynecessarytodecidewhethertoteachelementarysciencetoeveryoneonamassbasisortofindthegiftedfewan
AnOhioStateUniversitystudyhaslinkedbehaviorinyoungchildren【1】thetypeofjobtheirmotherhas.Motherswithcomplexoc
ThelandscapeoftheAmericanWestwasdramaticallyalteredduringthe20thcenturyasaresultofthe______constructionofdams
Apreviouslyunknowndisease,SARShasenteredourdailyvocabulary.Nowweliveinits【1】WhileSARS【2】centerstage,anancient
ThestrangestweatheroflastyearwaspossiblynotonEarth,butontheSun.Every11years【C1】______theSungoesthroughacyc
Thousandsofpeople______fromGreeceeveryyeartoworkinWestGermany.
Obviously,thepercapitaincomeofacountrydependsonmanythings,andanystatisticaltestthatdoesnottakeaccountofall
随机试题
泵若需自配电机,为防止电机超负荷,常按实际工作的()计算轴功率N,取(1.1~1.2)N作为选电机的依据。
关于胰腺炎诊断中血、尿淀粉酶检测的叙述不正确的是
男性,52岁。反复无痛性肉眼血尿伴条状血块2月,膀胱镜检见右输尿管口喷血,尿细胞学可见癌细胞。明确诊断后首选的治疗方法是
肾小球滤过率是指单位时间内
吊运灼热金属或危险品用钢丝绳的报废断丝数,取一般起重机用钢丝绳报废断丝数的(),其中包括由于钢丝表面磨蚀而进行的折减。
委托监理合同中,监理人应承担的义务包括( )。
某市公安局警察胡某、宋某接到报警,赶到现场,将酒后与他人斗殴的犯罪嫌疑人林某带回公安局询问。在询问期间,林某酒醉不醒,且行为狂乱,不仅打砸公安局办公室用品.而且自残身体。为保护林某自身与他人安全,胡某、宋某决定采取措施,控制醉酒人。请问,下列选项中,哪一举
将一个表面积为18平方厘米的正方体沿对角线切成两块对称的三棱柱(见图),并将这两块三棱柱重新拼接成一个大的三棱柱。则这个大三棱柱的表面积最大为()平方厘米。
若△ABC的三边为a,b、c,且满足a2+b2+c2=ab+ac+bc,则△ABC为().
这次到台湾访问交流,虽然行程匆匆,但是,看了不少地方,访了旧友,交了新知,大家走到一起,谈论的一个重要话题就是中华民族在21世纪的强盛。虽然祖国大陆、台湾的青年生活在不同的社会环境中,有着各自不同的生活经历,但大家的内心都深深铭刻着中华文化优秀传统的印记,
最新回复
(
0
)