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
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered t
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered t
admin
2009-02-10
19
问题
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered the causes of volcanic action. They know that the inside of the earth is very hot, but they are not sure exactly what causes the great heat. Some geologists have thought that the heat is caused by the great pressure of the earth’s outer layers. Or the heat may be left from the time when the earth was formed. During the last sixty years scientists have learned about radium, uranium, thorium and other radioactive elements. These give ont heat all the time as they change into other elements. Many scientists now believe that much of the heat inside the earth is produced by radioactive element.
Whatever the cause of the heat may be, we do know that the earth get hotter the farther down we dig. In deep mines and oil wells the temperature rises about 1 for each 50 feet. At this rate the temperature 40 miles below the earth’s surface would be over 4,0007 This is much hotter than necessary to melt rock. However, the pressure of the reek above keeps most materials from melting at their usual melting points. Geologists believe that the rock deep in the earth may be plastic, or putty-like. In other words, the rock yields slowly to pressure but is not liquid. But if some change in the earth’s crust re leases the pressure, the rock melts. Then the hot, liquid rock can move up toward the surface.
When the melted rock works its way close to the earth crust, a volcano may be formed. The melted rock often contains steam and other gases under great pressure. If the rock above often gives way, the pressure is released. Then the sudden expansion of the gases causes explosions. These blow the melted rock into pieces of different sizes and shoot them high in the air. Here they cool and harden into volcanic ash and cinders. Some of this material falls around the hole made in the earth’s surface. The melted rock may keep on rising and pour out as lava. In this way, volcanic ash, cinders and lava build up the cone-shaped mountains that we call volcanoes.
The cause for the heat in the interior of the earth is ______.
选项
A、radioactive element
B、the great pressure of the earth
C、not determined
D、volcanic action in the interior of the earth
答案
C
解析
根据第一段第三句,我们知道,对高温的成因有几种观点,但人们认识并不完全一致。因此,选C,而排除其他各项。
转载请注明原文地址:https://kaotiyun.com/show/BF6K777K
0
专业英语四级
相关试题推荐
ThroughouttheU.S.studentsaregettingouttheirNo.2pencils,readyendureastress-packedfourhoursofbubblinginanswers
A、Byusingcollegenoticeboard.B、Bystoppingpeopleonthestreet.C、Bytalkingtoclassmates.D、Bycallingsometargetpartic
Unlikeanyothercreatureonthisplanet,humanscanlearnandunderstand,withouthavingexperienced.Theycanthinkthemselve
Scientistsfordecadeshaveclashedoverwhetherevolutiontakesplacegraduallyorisdrivenbyshortspurtsofintensechange
Thefollowingaretwoexcerptsabouttheuseofmobilephonesinclassrooms.Readthetwoexcerptscarefullyandwriteanarticl
(1)It’shardtomissthem:theepitomeofcasual"geekchic"andorganizedwithinthewarrantyoftheirPalmPilots,theysipl
(1)St.Petersburg,theverynamebringstomindsomeofRussia’sgreatestpoets,writersandcomposers:Pushkin,Dostoevsky,
Aspeopleage,thebrainchangesinbothgoodwaysandbad. Ifyouareover20,yourcognitiveperformanceisprobablyalrea
MillionsofAmericansruntothebankorvisitautomatedtellermachineswhentheyneedcash.Theyusecreditcardswhentheywa
WaltDisneyisbelievedtopossessthefollowingabilitiesEXCEPTAccordingtothepassage,whatwasthepleasantsideofDisne
随机试题
糖化血红蛋白的临床意义是()。
男性,38岁,车祸伤及头部,当即出现右侧鼻唇沟变浅,右外耳道流出淡血性液体,右耳听力下降,CT示颅内少量积气。考虑患者出现了
板式橡胶支座极限抗压强度,部颁标准规定为()。
多向搅拌桩钻机就位必须正确,其孔位偏差不得大于(),钻杆垂直度偏差不得大于()。
下列关于专家判断法的信用风险评级方法说法错的是()。
【背景材料】生态文明贵阳国际论坛2014年年会7月11日在贵阳开幕。国务院总理李克强向论坛发来贺信。他表示,生态文明源于对发展的反思,也是对发展的提升,事关当代人的民生福祉和后代人的发展空间。中国把生态文明建设放在国家现代化建设更加突出的位置,坚持在发展
设X1,X2,…,X7是总体X~N(0,4)的简单随机样本,求P.
下列选项中,关于弹性分组环的叙述不正确的是()。
We’vehalvedthepriceofliterallythousandsofbooks,includinghundredsofbrandnewtitles.We’vealsotaken25%offaudiobo
NowWe’reTalking:HowVoiceTechnologyIsTransformingComputing[A]Likecastingamagicspell,itletspeoplecontrolthewor
最新回复
(
0
)