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
Earth Rocks on Most of the time, the ground feels solid beneath our feet. That’s comforting. But it’s also misleading becaus
Earth Rocks on Most of the time, the ground feels solid beneath our feet. That’s comforting. But it’s also misleading becaus
admin
2013-05-28
41
问题
Earth Rocks on
Most of the time, the ground feels solid beneath our feet. That’s comforting. But it’s also misleading because there’s actually a lot going on underground. Masses of land(called plates)slip, slide, and bump against each other, slowly changing the shape of continents and oceans over millions and billions of years.
Scientists know that Earth formed about 4. 5 billion years ago. They also know that our planet was hot at first. As it cooled, its outermost layer, called the crust(地壳), eventually formed moving plates. Exactly when this shift happened, however, is an open question.
Now, an international group of researchers has an answer. They’ve found new evidence suggesting that Earth’s crust started shifting at least 3. 8 billion years ago. The new estimate is 1.3 billion years earlier than previous ones.
Not long before 3. 8 billion years ago, lots of asteroids(小行星)were hitting Earth, keeping its crust in a hot, melted state. After the hard crust formed, much of it sank at various times into the planet’s hot insides. There, it melted before returning to the surface.
In some places, however, the crust never sank. One of the oldest such places is in Greenland, in an area called the Isua supracrustal(上地壳)belt. The rocky crust there is between 3. 7 and 3. 8 billion years old. The belt was once part of the seafloor, but now it is exposed to air.
The researchers recently took a close look at the Isua supracrustal belt. They noticed long, parallel cracks in the rock that have been filled in with a type of volcanic rock.
To explain this structure, the scientists propose that tension in the crust caused the seafloor to crack open long ago. Hot, liquid rock, called magma(岩浆), flowed up slowly from deep inside Earth to fill the cracks. Finally, the whole area cooled, forming what we see today.
That explanation, plus chemical clues inside the rock, suggests that the Isua supracrustal belt was once part of a plate under the ocean, beginning around 3. 8 billion years ago.(2011年)
It took a long time for the melted crust to become hard.
选项
A、Right
B、Wrong
C、Not mentioned
答案
C
解析
题干大意:融化的地壳用了很长时间才变硬。文章信息没有提到任何有关地壳用多长时间变硬的信息,故答案选C。
转载请注明原文地址:https://kaotiyun.com/show/XiLd777K
本试题收录于:
职称英语理工类A级题库职称英语分类
0
职称英语理工类A级
职称英语
相关试题推荐
ScientistsDevelopWaysofDetectingHeartAttackGermanresearchershavecomeupwithanewgenerationofdefibrillators(除颤
ScientistsDevelopWaysofDetectingHeartAttackGermanresearchershavecomeupwithanewgenerationofdefibrillators(除颤
AnimalsintheDesertSomedesertanimalscansurvivetheverystrongsummerheatanddrynessbecausetheyhaveveryunusualcha
TransportationuseatoBeMuchSlowerthanItIsNowFormanyyearsintiledesert,camelsuse
AUndeniableMiffsAchievementsBRewardsFollowingtheUSFinancialInjectionCMir’sProblemYearDMirRegardedasa
ThirstforOilWorldwideeveryday,wedevourtheenergyequivalentofabout200millionbarrelsofoil.MostoftheenergyonE
EconomicReforminChinaMoreUSsinologistshaveexpressedconfidenceinChina’seconomicreformandtheprospectsforChina’s
AFactorsLeadingtoEnergyWasteBHomeAppliancesCPropsalstoCutEnergyConsumptionDEnergyConsumptionTestETerawa
Thenurseryisbrightandcheerful.
Europa’sWateryUnderworldEuropa,oneofJupiter’s63knownmoons,looksbrightandicyonthesurface.Butappearancescan
随机试题
下列肿瘤中,属于恶性肿瘤的是
具有行气血作用的是什么气
三栏式明细账不适合()账户的明细账采用。
投资性资产通常分为可配置投资性资产和不可配置投资性资产两类。下列属于不可配置投资性资产的有()。
根据专家推断,2006年内人民币将升值3%左右,按4月5日外汇市场美元兑人民币汇率的中间价推算,人民币对美元的汇率到2006年年底将跌至多少?( )4月5日人民币对美元汇率的收盘价是( ),创汇改以来的新高。
已知甲校学生人数是乙校学生人数的40%,甲校女生人数是甲校学生人数的30%,乙校男生人数是乙校学生人数的42%,那么,两校女生总数占两校学生总数的()。
为了区分类中重载的同名的不同方法,要求()。
Woman:Thankyouverymuchforyourhelp.Man:_________
1Realestateagentsareemployedbyrealestateagenciesthatsellorrentpropertyormanage,appraise,ordeveloprealestate
In"Whenshegoestoworkisherowndecision",theitalicizedpartis______.
最新回复
(
0
)