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
90
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.
This passage is probably_____.
选项
A、a newspaper advertisement
B、a chapter of a novel
C、an excerpt from a textbook
D、a scientific report of new findings
答案
C
解析
主旨大意题。由本文的语言风格和描述内容可以判定这篇文章既不是商业性的,也不是文学性的,同时文中叙述的内容具有科普性质,不可能是太前沿性的,因此A、B、D三项都不正确,选项C为此题答案。
转载请注明原文地址:https://kaotiyun.com/show/EuY7777K
0
大学英语四级
相关试题推荐
Pricesdeterminehowresourcesaretobeused.Theyarealsothemeansbywhichproductsandservicesthatareinlimited【B1】___
It’sdifficulttoimaginetheseaeverrunningoutoffish.It’ssovast,sodeep,so【B1】______.Unfortunately,it’snot【B2】____
Inmanycountries,authorityisseldomquestioned,eitherbecauseitishighlyrespected,orbecauseitis【B1】_______.Sometimes
A、Theexamquestionsweretoodifficult.B、Thequestionshadlittleconnectionwiththecourse.C、Hecouldn’tfinishthequestio
A、BecausehehasfinishedhisstudyofadvancedMathematics.B、Becausehewantstoenjoyhimselfbeforeexamination.C、Becauseh
Inrecentyears,moreandmoreforeignersareinvolvedintheteachingprogramsoftheUnitedStates.Boththeadvantagesandth
A、TheaccuracyofGPSsystem.B、ThecostofGPSdevices.C、TheweightofGPSdevices.D、Thespeedofinformationtransmission.A
A、Thepositionwhichthesystemprovides.B、Theinformationtransmittedfromsatellites.C、Thesatellitesthatrevolvearoundth
秦朝是第一个统一(unify)中国的朝代。秦始皇作为中国的首个皇帝而被人们所记住。他以绝对的权威进行无情地统治,甚至破坏了与他的理念不一致的古代惯例和文学。虽然秦朝只持续了15年,但它对于中国文化的影响是巨大的。它引入了封建制度(feudalsystem
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,themantlemadeofsilicate(硅酸盐)thataresemi-moltenat
随机试题
(2021年德州齐河)儿童遗忘的进程是不均衡的,一般呈现的趋势是()
交流测速发电机的励磁绕组必须接在频率和大小都不变的交流励磁电压上。()
什么叫回流比?
确定宫颈癌临床分期的必要检查为
患儿,女,3岁,口腔溃疡2天,疼痛拒食、烦躁,流口水,小便黄,大便干。查体:口腔口舌面多处溃疡,周围红赤,口臭,舌红苔黄,脉滑数。诊断为
治疗咽喉红肿疼痛,兼有肺热咳嗽痰多者,应首选
政府应当维护和促进经济社会的可持续发展,这是指政府的()
根据下面材料回答问题。根据资料,下列表述不正确的一项是()。
据一项在几个大城市所做的统计显示,餐饮业的发展和瘦身健身业的发展呈密切正相关。从1985年到1990年,餐饮业的网点增加了18%,同期在健身房正式注册参加瘦身健身的人数增加了17.5%;从1990年到1995年,餐饮业的网点增加了25%,同期参加瘦身健身的
Somepeoplearealwayslate,forschool,forwork,orforanyappointment,nomatterhowimportantitis.Youaretosuggestsom
最新回复
(
0
)