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
2013-04-06
25
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/wFr7777K
0
大学英语四级
相关试题推荐
A、Bymixingitwithspecialoils.B、Bycombiningitwithdifferentflavors.C、Byaddingsodawater.D、Byheatingit.C
A、Sheprefersapples.B、She’sonadiet.C、Therewasnothingelsetoeat.D、It’sonlyasnack.CM:Whyareyoueatingthatapple
Researchersknowtherearemanydrugsthatcanalterourbodilyprocessesinsuchaway【C1】______affectouremotionalexperience
Researchersknowtherearemanydrugsthatcanalterourbodilyprocessesinsuchaway【C1】______affectouremotionalexperience
Ifyouwanttostayyoung,sitdownandhaveagoodthink.ThisistheresearchfindingofateamofJapanesedoctors,whosayt
TherearemanytheoriesaboutthebeginningofdramainancientGreece.Theonemostwidelyacceptedtodayisbasedontheassum
A、He’dbettersubmithisresumeatonce.B、Notallapplicantswillbeinterviewed.C、Shedoesneedhishelpforthemoment.D、Th
5QuestionsontheOriginsofChristmasThetraditionsweassociatewithChristmashaveevolvedoverthecenturies.Hereare
For______footballplayers,injuriesareanoccupationalhazardwhichseemsunaviodable.
TheAncientGreekOlympicsToday’sOlympicGamesarebasedonwhattookplaceatOlympia,inGreece,nearlythreemillennia
随机试题
渗出性腹泻的特点为:()
零售企业的特点有哪些?
地龙在补阳还五汤中主要配伍意义是
公积金个人住房贷款和商业银行自营性个人住房贷款的区别有()。
监狱作为国家机器的重要组成部分,是阶级矛盾不可调和的产物和表现,是随着国家的产生而产生的,是掌握国家政权的阶级进行统治的工具。()
麻雀战术是一种化整为零,即将整个战争细分为许多个局部小组织的战斗,化机械笨重的作战方式为灵活轻巧的作战方式,通过反复的分散和整合,迷惑敌人,分散敌方的注意力,并集中优势兵力群起而歼之。根据上述定义,以下哪种作战方式属于麻雀战术?()
属于对额外变量进行实验后控制的方法是
在一项关于颜色对生产率作用的研究中,让100位工厂工人中的50位从其土褐色的工作问移到一间颜色明亮的工作间。这些工人和剩下在土褐色工作间的工人都提高了其生产率,这可能是因为研究人员们在研究中同时对两个群体的工作都很感兴趣。下面哪项,如果正确,会对上面提供的
(2016年真题)甲、乙二人驾驶摩托车夺取吴某挎包,因车速过快将吴某带倒,致其重伤。甲、乙的行为应认定为
Inmanybusinesses,computershavelargelyreplacedpaperwork,becausetheyarefast,flexible,anddonotmakemistakes.Asone
最新回复
(
0
)