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
The collapse of the Earth’s magnetic field—which guards the planet and guides many of its creatures—appears to have started abou
The collapse of the Earth’s magnetic field—which guards the planet and guides many of its creatures—appears to have started abou
admin
2013-01-28
46
问题
The collapse of the Earth’s magnetic field—which guards the planet and guides many of its creatures—appears to have started about 150 years ago, the New York Times reported last week.
The field’s strength has decreased by 10 or 15 percent so far and this has increased the debate over whether it signals a reversal of the planet’s lines of magnetic force.
During a reversal, the main field weakens, almost vanishes, and reappears with opposite polarity (极). The transition would take thousands of years. Once completed, compass needles that had pointed north would point south. A reversal could cause problems for both man and animals. Astronauts and satellites would have diffculties. Birds, fish and animals that rely on the magnetic field for navigation would find migration confusing. But experts links between past field reversals and species extinctions.
Although a total transition may be hundreds or thousands of years away, the rapid decline in magnetic strength is already affecting satellites. Last month, the European Space Agency approved the world’s largest effort at tracking the field’s shifts. Now a group of satellites called Swarm is to monitor the collapsing field with far greater precision. " We want to get some idea of how this would evolve in the near future, just like people trying to predict the weather, " said Gauthier Hulot , a French geophysicist working on the satellite plan. "I’m personally quite convinced we should be able to work out the first predictions by the end of the mission. "
No matter what the new findings, the public has no reason to panic. Even if a transition is coming on its way, it might take 2,000 years to mature. The last one took place 780,000 years ago, when early humans were learning how to make stone tools. Deep inside the Earth flow hot currents of melted iron. This mechanical energy creates electromagnet-ism. This process is known as the geophysical generator. In a car’s generator, the same principle turns mechanical energy into electricity.
No one knows precisely why the field periodically reverses. But scientists say the responsibility probably lies with changes in the disorderly flows of melted iron, which they see as similar to the gases that make up the clouds of Jupiter.
The cause of the transition of the Earth’s magnetic field comes from______.
选项
A、the movement deep inside the Earth
B、the periodical reverses of the Earth
C、the force coming from outer space
D、the mechanical movement of the Earth
答案
D
解析
本题考查考生的推断能力。文中最后一段的内容:没有人知道究竟为什么磁场会有周期性的转变。但是科学家认为这与地球深层的熔铁无序流动改变有关,这就类似于构成木星星云的气体。由此可以知道,D项符合题意。
转载请注明原文地址:https://kaotiyun.com/show/Bt1O777K
0
考博英语
相关试题推荐
I’d_______hisreputationwithotherfarmersandbusinesspeopleinthecommunity,andthenmakeadecisionaboutwhetherornot
Therearegreatcareersinwhichtheincreasingemphasisisonspecialization.Youfindthesecareersinengineering,inproduct
Itwasnotuntilshereturnedhome_____sherealizedshehadalmostwastedtenofhervaluablehours.
Relentlessrainstriggeredheavyfloodinginnineprovinces,where68personswerekilled.Thegovernmentpledgedrelieffundsof
TheAleuts(阿留申人)werenamedsobyRussians,buttheycallthemselvesUnanganwhichmeans"thepeople."Theyarenativeinhabit
Superstitionisadifficultquestion.WecannotquitesaythatsuperstitioninBritainisdead.Itshistoryisboth【76】longand
Certainlynocreatureintheseaisodderthanthecommonseacucumber.Alllivingcreatures,especiallyhumanbeings,havethei
Manyoftheconditionsthatpopulationpressures-overcrowding,unemployment,poverty,hungerandillness______leadtodissatis
Shewasonceabeautifulmodelbuttheyearshad______herfeatures.
随机试题
股利相关论的重要代表人物不包括()
急性心梗的常见先兆症状是
A.被认识接纳的需要B.信息获取的需要C.安全感需要D.关心尊重的需要E.早日康复的需要
根据《突发公共卫生事件应急条例》规定,县级以上人民政府在防治突发事件时,应当
A.五倍子B.五味子C.乌梅D.诃子E.罂粟壳能敛肺,涩肠,降火的是
总包单位依法将建设工程分包时,分包工程发生的质量问题,应( )。
公路工程符合竣工验收条件后,建设单位已向交通运输主管部门提交竣工验收申请。交通运输主管部门对申请人递交的材料进行审查,对于符合验收条件的,应自收到申请文件之日起()个月内组织竣工验收。
我国行政诉讼法规定,对于因征税问题引起的争议,当事人可以选择适用复议或诉讼程序,如选择复议程序,对复议决定仍不服的,可以向法院起诉。()
以下关于常用经济术语的说法,错误的是()。
ThreeConceptsinArtHistoryI.Commonalities-Certainchunkof【T1】_____,【T1】______withinwhich【T2】_____wereshared【T2】_____
最新回复
(
0
)