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
2016-10-07
100
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/6uY7777K
0
大学英语四级
相关试题推荐
A、ShewillcallBobwhenshecomestotownagain.B、ShewillfindtimetomeetBobonhernextvisit.C、Shewillvisitthetown
Inmanycountries,authorityisseldomquestioned,eitherbecauseitishighlyrespected,orbecauseitis【B1】_______.Sometimes
Inmanycountries,authorityisseldomquestioned,eitherbecauseitishighlyrespected,orbecauseitis【B1】_______.Sometimes
Inmanycountries,authorityisseldomquestioned,eitherbecauseitishighlyrespected,orbecauseitis【B1】_______.Sometimes
Weoftenpassonlittlebitsofinformationtoourchildren,notknowingiftheyaretrue,andonlybecausetheywere【B1】_______
Weoftenpassonlittlebitsofinformationtoourchildren,notknowingiftheyaretrue,andonlybecausetheywere【B1】_______
Americansbelievethatindividualsmustlearnto【B1】_______themselvesorrisklosingfreedom.Thismeansachievingbothfinanci
A、ThemancouldnotwaittoseeSusan.B、Susaniseagertopasstheinformationsheknows.C、Susantalkstopeopleonlyonthep
DueAttentionShouldBePaidtoInternetSafety1.很多网民的利益及隐私受到侵犯和威胁2.造成这种现象的原因是……3.为了提高网络安全,我认为……
随机试题
甲公司经常派业务员乙与丙公司订立合同。乙调离后,又持盖有甲公司公章的合同书与尚不知其已经调离的丙公司订立一份合同,并按照通常做法提走货款,后逃匿。对此甲公司并不知情。丙公司要求甲公司履行合同,甲公司认为该合同与己无关,予以拒绝。对此,下列表述正确的是(
ABS、SAN、HIPS都是苯乙烯系列合成树脂。
行政环境的基本属性有:________、________、________、________。
全国各族人民团结凝聚的核心是
Thefactoryhasdonegoodhonourtothegovernmentandthepeoplearoundsothatvisitorscometoit______.
用以复现和保存计量单位量值,经国务院计量行政部门批准作为统一全国量值最高依据的计量器具是()。
按照《公约》的规定,一项发盘的内容必须十分肯定,只有具备()才算十分确定。
Ahouseisthemostexpensivethingmostpeoplewilleverbuy.Veryfewpeoplehaveenoughmoneyoftheirowntobuyahome,so
不等式3|x-2|+x≤10的解集为()
TheWorld’sLongestBridgeRumorhasitthatalegendarysix-headedmonsterlurksinthedeepwatersoftheTyrhenianSeabe
最新回复
(
0
)