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
The Earth comprises three principal layers: the dense, iron-rich core, the mantle made of silicate (硅酸盐) that are semi-molten at
admin
2018-05-09
53
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.
The Earth’s crust_____.
选项
A、can be classified into two types
B、is formed along the margins of the plates
C、consists of semi-molten rocks
D、is about 70 to 100 kilometers thick
答案
A
解析
事实细节题。选项A与文章第1段第2句所述一致,为正确答案。此类题可采用排除法。根据第2段第2句的内容可以知道选项B所指的只是地壳中的一种,而不是所有地壳。选项C与文章第1句的内容不符。选项D的主语应该是地壳和上层的地幔,不仅仅是地壳。
转载请注明原文地址:https://kaotiyun.com/show/zB47777K
0
大学英语四级
相关试题推荐
Manyprivateinstitutionsofhighereducationaroundthecountryareindanger.Notallwillbesaved,andperhapsnotalldeser
HalloweenA)OnOctober31st,dozensofchildrendressedincostumesknockontheirneighbors’doorsandyell"TrickorTreat
InonlytwodecadesAsianAmericanshavebecomethefastest-growingU.S.minority.Astheirchildrenbeganmovingupthroughthe
AnewreportreleasedbytheAmericanFederationofTeachers(AFT)remindsusofatopiceducationwritersalmostneveraddress—th
SomeAmericansarealittlenervousaboutthenation’sfuture,butothersfeelsecure,knowingthatthemantheyconsiderthemo
SomeAmericansarealittlenervousaboutthenation’sfuture,butothersfeelsecure,knowingthatthemantheyconsiderthemo
DevelopHealthyEatingHabitsinYourChildrenA)Whatdoyouthinkyourchildrenareservedatschool?Thechildrenwereser
KeepOurSeasCleanA)Bytheyear2050itisestimatedthattheworld’spopulationcouldhaveincreasedtoaround12billion
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,themantlemadeofsilicate(硅酸盐)thataresemi-moltenat
A、AGooglemanagerissupportingtheadvancementofAI.B、TheWatsonsupercomputerhasdefeatedthegreatestplayersofJeopardy
随机试题
国务院测绘行政主管部门受理或者接到一次性测绘申请初审意见后5个工作日内送军队测绘主管部门会同审查,并在接到会同审查意见后()个工作日内作出审查决定。
《中华人民共和国环境影响评价法》明确了建设单位的违法行为和处罚,其中不能承担法律规定的行政处分责任的建设单位人员是()。
下列工程施工过程中,属于侵权责任的情形有()。【2010年考试真题】
对于债务人和债权人而言申请破产只是一项民事权利。()
关于契税计税依据的下列表述中,符合法律制度规定的有()。
关于儿童身体发展的说法正确的是()。
劳动定额法属于()。
社会劳动和罪犯劳动都具有谋求自我发展的特性。()
优柔寡断:抉择
Duringthefire,he______peopleintogroupswhichcarriedsandandwatertothrowontotheflames.
最新回复
(
0
)