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
2016-04-30
17
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/Eqe7777K
0
大学英语四级
相关试题推荐
Howdowegetmorepeopletoincreasetheirconsumptionofiron-richfoods?Manynutritionists【C1】______theincreaseofanumber
Howdowegetmorepeopletoincreasetheirconsumptionofiron-richfoods?Manynutritionists【C1】______theincreaseofanumber
WhoLives?WhoDies?WhoDecides?A)SomehavecalleditaRighttoDiecase.OthershavelabeleditaRighttoLivecase.Onegr
Manyoftoday’scollegestudentsaresufferingfromaformofshock.Lisaisagoodexampleofastudentinshock.Sheisanatt
Manyoftoday’scollegestudentsaresufferingfromaformofshock.Lisaisagoodexampleofastudentinshock.Sheisanatt
UniversitiesBranchOutA)Asneverbeforeintheirlonghistory,universitieshavebecomeinstrumentsofnationalcompetitionas
Pricesdeterminehowresourcesaretobeused.Theyarealsothemeansbywhichproductsandservicesthatareinlimitedsupply
HelicopterMomsVS.Free-RangeKidsA)Wouldyouletyourfourth-graderridepublictransportationwithoutanadult?Probablynot
Therearerareinstanceswhenjusticealmostceasestobeanabstract【C1】______.Rewardor【C2】______areoutquiteindependentof
Therearerareinstanceswhenjusticealmostceasestobeanabstract【C1】______.Rewardor【C2】______areoutquiteindependentof
随机试题
脊髓灰质炎病人的传染性排泄物主要是()
我国肝硬化的常见病因是()。
A.气相色谱法B.碘量法C.微生物法D.紫外分光光度法E.非水溶液滴定法在《中国药典》中,维生素B1片含量的测定方法是()。
[2012年第75题]工程建设强制性标准不涉及以下哪个方面的条文?
背景资料:某机电工程由业主邀请同行业有业绩的A、B、C、D、E、F六家施工单位进行机电安装工程总承包的投标,工程采用总价包干,变更在分部工程价±5%范围内不做调整。工期18个月。接到邀请后,F公司因任务饱满,E公司与F公司进行协商由F公司为E公司陪标,
一般地,财务处理系统主要由初始设置和()模块组成。
根据《人民币银行结算账户管理办法》的规定,一般存款账户不能办理的业务是()。
在社区工作中,社会工作者与社区居民一起讨论,互相交换意见,并由居民做出合乎自己愿望的决定,是遵循了社区工作的()的实践原则。
微博、QQ、BBS、E—mail等信息技术在教育活动中都可作为()的工具。
在中国共产党创建初期和国民革命时期,标志着毛泽东思想萌芽的是()
最新回复
(
0
)