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
69
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.
According to the second paragraph, the formation of the Atlantic Ocean is the example of_____.
选项
A、spreading contacts
B、the influence of volcanic eruptions
C、converging contacts
D、transform contacts
答案
A
解析
事实细节题。第2段主要分成两部分:第一部分谈板块活动的三种形式,第二部分分别举例说明。其中在说明spreading contacts时,引用了大西洋的例子:“The Atlantic Ocean formed like this…”,所以答案为A。
转载请注明原文地址:https://kaotiyun.com/show/buY7777K
0
大学英语四级
相关试题推荐
A、Theydon’tknowhowtogettoMike’shome.B、Theyarediscussingwhentomeetagain.C、Theywenttothesamepartysometimea
It’sdifficulttoimaginetheseaeverrunningoutoffish.It’ssovast,sodeep,so【B1】______.Unfortunately,it’snot【B2】____
Inmanycountries,authorityisseldomquestioned,eitherbecauseitishighlyrespected,orbecauseitis【B1】_______.Sometimes
Weoftenpassonlittlebitsofinformationtoourchildren,notknowingiftheyaretrue,andonlybecausetheywere【B1】_______
Weoftenpassonlittlebitsofinformationtoourchildren,notknowingiftheyaretrue,andonlybecausetheywere【B1】_______
Weoftenpassonlittlebitsofinformationtoourchildren,notknowingiftheyaretrue,andonlybecausetheywere【B1】_______
A、NotgiveanysuggestionstoJack.B、NotseeJackanymore.C、NotlistentoJack’swords.D、NotsavehiswordsonJack.A男士说:我告
We’renowwitnessingtheemergenceofanadvancedeconomybasedoninformationandknowledge.Physical【B1】_______,rawmaterials
ID-BasedTrainTicketBookingSystem1.实名制购买火车票已在很多城市开始试行2.有人认为这样做是社会进步的表现,也有人认为它可能会带来一些问题3.在我看来……
Comparativelyfewfresh-waterspeciesoffishesarelimitedintheirdistributiontoasingleriversystem,yetnotmanyarefou
随机试题
简述慢性血源性骨髓炎手术指征和禁忌证。
第二类危险源的内容不包括( )。
我国经营性金融机构包括()。
下列各项中关于会计账簿的基本内容中,说法正确的有()。
【2015年河北石家庄.单选】马卡连柯提出的“要尽量多地要求一个人,也要尽可能地尊重一个人”,反映了德育的()。
软件能力成熟度模型CMM(Capability Maturity Model)描述和分析了软件过程能力的发展和改进程度,确立了一个软件过程成熟程度的分级标准。该模型的第2级为可重复级,它包含了(62)关键过程域。
"Themorethatyouread,themorethingsyouwillknow.Themorethatyoulearn,themoreplacesyou’llgo."Thesesimple-but-t
Alargepartofeffectiveleadershipisdependentonsomethingcalled"style".Butstyleisdifficulttoteach,andwhatmakes
Everyoneknowsthathumanlanguagecanbeasuperbmeansofcommunication.Therefore,itcanbedamnably【M1】______
Whatisthebesttitleforthispassage?
最新回复
(
0
)