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 Earth comprises three principal layers: the dense, iron-rich core, the mantle made of silicate(硅酸盐)that are semi-molten at d
The Earth comprises three principal layers: the dense, iron-rich core, the mantle made of silicate(硅酸盐)that are semi-molten at d
admin
2016-09-21
67
问题
The Earth comprises three principal layers: the dense, iron-rich core, the mantle made of silicate(硅酸盐)that are semi-molten at depth, and the thin, solid-surface crust. There are two kinds of crust, a lower and denser oceanic crust and an upper, lighter continental crust found over only about 40 percent of the Earth’s surface. The rocks of the crust are of very different ages. Some continental rocks are over 3,000 million years old, while those of the ocean floor are less than 200 million years old. The crusts and the top, solid part of the mantle, totaling about 70 to 100 kilometers in thickness, at present appear to consist of about 15 rigid plates, 7 of which are very large. These plates move over the semi-molten lower mantle to produce all of the major topographical(地形学的)features of the Earth. Active zones where intense deformation occurs are confined to the narrow, interconnecting boundaries of contact of the plates.
There are three main types of zones of contact: spreading contacts where plates move apart, converging contacts where plates move towards each other, and transform contacts where plates slide past each other. New oceanic crust is formed along one or more margins of each plate by material issuing from deeper layers of the Earth’s crust, for example, by volcanic eruptions(爆发)of lava(火山熔岩)at mid-ocean ridges. If at such a spreading contact the two plates support continents, a rift(裂缝)is formed that will gradually widen and become flooded by the sea. The Atlantic Ocean formed like this as the American and Afro-European plates moved in opposite directions. When two plates carrying continents collide, the continental blocks, too light to be drawn down, continue to float and therefore buckle(起褶皱)to form a mountain chain along the length of the margin of the plates.
Seriously-deformed zones appear _____.
选项
A、whenever the crusts move over mantle
B、when the plates move towards each other
C、in the narrow boundaries where two plates meet
D、to be the major topographical feature of the Earth
答案
C
解析
C是对第1段最后一句的同义改写。文章中没有提到A中the crusts move over mantle这种现象;B提到的现象在第2段第1句才讨论到,与题干无关;文中也没有提到严重变形的地区是地球的主要地形特征,因此D不正确。
转载请注明原文地址:https://kaotiyun.com/show/mtY7777K
0
大学英语四级
相关试题推荐
TheArtofFriendshipA)OneeveningafewyearsagoIfoundmyselfinananxiety.Nothingwasreallywrong—myfamilyandIwer
A、Sheisn’thavingmuchtrouble.B、Sheunderstoodthereadingyesterday.C、Sheunderstandsverylittle.D、Sheisgoodatintensi
Doyoufindgettingupinthemorningsodifficultthatit’spainful?Thismightbecalledlaziness,butDr.Kleitmanhasanew
UnitedNations’talksonclimatechangehaveendedinBangkokwithlittlesignofprogress.Therearestillmajor【B1】______betwe
UnitedNations’talksonclimatechangehaveendedinBangkokwithlittlesignofprogress.Therearestillmajor【B1】______betwe
It’sdifficulttoimaginetheseaeverrunningoutoffish.It’ssovast,sodeep,so【B1】______.Unfortunately,it’snot【B2】____
UniversitiesBranchOutA)Asneverbeforeintheirlonghistory,universitieshavebecomeinstrumentsofnationalcompetitionas
A、Ithasnodifferencefromothercells.B、Itcanonlybecomeacertaintypeofcell.C、Itcan’tbecomeakidneycell.D、Itmain
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,themantlemadeofsilicate(硅酸盐)thataresemi-moltenatd
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,themantlemadeofsilicate(硅酸盐)thataresemi-moltenat
随机试题
女性,18岁,体榆发现心脏杂音来诊。平时不能耐受较大的体力活动,无双下肢水肿及夜间呼吸困难史,易感冒。查体:血压130/80nmmHg,心率90次/分。S1、S2稍高A2SM3/6反流样向左腋下传导,L4、5可闻收缩期Click,下蹲位站立后C1ic
口咽肿瘤最常见的颈淋巴结转移区为
黑色素瘤为
关于民事行为,下列说法中错误的是()。
产品定价首要考虑到的因素是()。
甲设计公司为增值税小规模纳税人,2014年6月提供设计服务取得含增值税价款206000元,冈服务中止。退还给客户含增值税价款10300元,并开具红字专用发票。已知小规模纳税人增值税征收率为3%,甲设计公司当月应缴纳增值税税额的下列计算中,正确的是(
人民法院收到债权人提出的破产申请后,如果债务人表示有异议,人民法院应在法定期限内决定是否立案受理。该法定期限是()。
办一次聚会准备邀请160个客人,预计平均每3个要花100块钱,则至少要有多少经费?
某次知识竞赛试卷包括3道每题10分的甲类题,2道每题20分的乙类题以及1道30分的丙类题。参赛者赵某随机选择其中的部分试题作答并全部答对,其最终得分为70分。问赵某未选择丙类题的概率为多少?()
LadiesandGentlemen,Welcometothiselectronicsexhibition.Hereyoucanfindalmostallofthe【T1】______productsabouto
最新回复
(
0
)