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
2013-02-24
14
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.
Seriously-deformed zones appear _______.
选项
A、whenever the crusts move over mantle
B、when the plates move towards each other
C、in the narrow boundaries where two plates meet
D、to be the major topographical feature of the Earth
答案
C
解析
选项C是对该句的同义改写。
转载请注明原文地址:https://jikaoti.com/ti/uLwFFFFM
0
大学英语四级
相关试题推荐
Ifyouweretobeginanewjobtomorrow,youwouldbringwithyousomebasicstrengthsandweaknesses.Successorfailureinyou
Tragedy,suddenandterrible,hasagainstruckanAmericanschool:fifteenliveswerelostandacityandanationleftwithsca
ThanksgivingisAmerica’snationalholidayforgivingthankstoGod.ThanksgivingDayhasaspecial【S1】______forAmericansbecau
ThanksgivingisAmerica’snationalholidayforgivingthankstoGod.ThanksgivingDayhasaspecial【S1】______forAmericansbecau
A、Colleagues.B、Classmates.C、Husbandandwife.D、Fatheranddaughter.C关键词题。女士说这件外套是男士在追求她的时候给她买的,男士表示肯定,并说这件外套已经旧了,他应该为女士另买一件新
Whentheearthwasborntherewasnoocean.Thegraduallycoolingearthwasenvelopedinheavylayersofcloud,which【S1】______m
A、Byburninghydrogen.B、Bycoolingotherplanets.C、Byheatingupperlayers.D、Bygivingoutradiation.A题干询问太阳如何产生能量。对话中男士说太阳是
A、Becauseitprovidesprecisedirection.B、Becauseitisaffordabletoordinaryusers.C、Becauseitisthetrendofthecentury.
A、Two.B、Three.C、Four.D、Five.B
A、Three.B、Twenty-four.C、Twohundred.D、Eight.A该题同样考查对数字的捕捉情况。而和religion同时出现的是数字three,因此选择选项A。
随机试题
左向右分流型先天性心脏病患儿生长发育落后是由于
哪些药物的A环含有3-酮-4-烯的结构
关于车牌自动识别装置的功能,下列说法错误的是()。
同家预算作为国家的基本财政计划,是国家财政实行宏观控制的主要依据和主要手段。()
根据《专利法》的规定,专利申请人在外国或中国第一次提出专利申请后,在下列期限内,又在中国就相同主题提出专利申请的,可以享有优先权的有()。
事物度的原理,要求我们要注意“适度”的原则,根据情况决定能不能超越和破坏事物的度。()
数据模型按不同的应用层次分为三种类型,它们是______数据模型、逻辑数据模型和物理数据模型。
有如下程序:#inc1ude<iostream>usingnamespacestd;c1assMyClass{public:MyClass(){++count;)~MyClass(){——c
假设某台式计算机的内存储器容量为128MB,硬盘容量为10GB。硬盘的容量是内存容量的()。
Theageofgildedyouth(纨绔子弟)isover.Today’sunder-thirtiesarethefirstgenerationforacenturywhocanexpectalowerli
最新回复
(
0
)