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
考研
The collapse of the Earth’s magnetic field—which guards the planet and guides many of its creatures—appears to have started seri
The collapse of the Earth’s magnetic field—which guards the planet and guides many of its creatures—appears to have started seri
admin
2012-02-27
73
问题
The collapse of the Earth’s magnetic field—which guards the planet and guides many of its creatures—appears to have started seriously about 150 years ago, the New York Times reported last week.
The field’s strength has decreased by 10 or 15 per cent 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. 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 difficulties. Birds, fish and animals that rely on the magnetic field for navigation would find migration confusing. But experts said the effects would not be a big disaster, despite claims of doom and vague evidence of 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. A group of new 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 electromagnetism. 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.
According to the experts, the reversal of the Earth’s magnetic field would ______.
选项
A、destroy almost all the creatures on the Earth
B、cause some species extinctions on the Earth
C、not be as disastrous as the previous one
D、cause no big trouble for man and animals
答案
D
解析
第三段最后一句:但是专家说这种影响不会造成大的灾难,尽管世界末日之称以及一些不明确的证据把物种灭绝与上一次地球磁场转移相提并论。
转载请注明原文地址:https://kaotiyun.com/show/fOmi777K
0
在职申硕(同等学力)英语
相关试题推荐
Somepeoplefeelsadaboutglobalizationbecausetheybelieveitwill______Internetwasoriginallydesigned______
Thewriterappliedforthejobbecause______Whatwasthewriter’sopinionofthepsychologist?
I(sawthat)thelastupdatewasmadein(Januaryof)2002,soI(wonderedthat)thewebmaster(hadabandoned)thesite.
RacingtheclockeverydayissuchanexhaustingeffortthatwhenIactuallyhaveafewfreemoments,Itendtocollapse.
WillAmericansgoforAT&T’splanofpushingthewirelessservicesintheU.S.?
Inflationisaperiodofrapidrisesinprices.Whenyourmoneybuysfewergoodssothatyouget【C1】______forthesameamount
A:Youseemtohavealotofworkatyouroffice.You’vealwaysbeenstayinglateandworkingovertime.B:______.
FormaccountissuedA.usuallymadeinthe(56)______ofacheckB.Aterminationnoticeshouldbe(57)______bythepersonneldepar
A.formB.accountC.issuedA.usuallymadeinthe【T1】______ofacheckB.Aterminationnoticeshouldbe【T2】______bytheperso
Thewaypeopleholdtothebeliefthatafun-filled,painfreelifeequalshappinessactuallyreducestheirchancesofeverattai
随机试题
背景:某工程地下2层,地上15层,现浇钢筋混凝土框架结构,由于局部技术难度大,业主采用了邀请招标方式,择优选择了其中一家作为中标单位,并与其签订了工程施工承包合同,承包工作范围包括土建、机电安装和装修工程。该工程开工日期为2011年4月1日,合同工期为1
不能和磺胺类药物合用的局麻药是
下列关于增量内部收益率法的说明中,正确的是()。
一般而言,影响行业市场结构变化的因素包括()。Ⅰ.企业的质量Ⅱ.企业的数量Ⅲ.进入限制程度Ⅳ.产品差别
马斯格雷夫与罗斯托应用经济发展阶段理论来解释公共支出的不断增长,并将经济发展划分为几个阶段,其中包括()。
强调自我对健康成长和环境适应的作用以及自我的自主性,人格发展包括了集体成熟、自我成长和社会关系三个不可分割的过程。这种观点的提出者是()。
人们把下水道的井口和盖子设计成圆形,主要是为了美观。()
中国特色社会主义理论体系,就是包括邓小平理论、“三个代表”重要思想以及科学发展观等重大战略思想在内的科学理论体系。
(2001年试题,一)设y=e*(C1sinx+C2cosx)(C1,C2为任意常数)为某二阶常系数线性齐次微分方程的通解,则该方程为________________.
Thesegoodsaresoldatreducedprices,________.
最新回复
(
0
)