首页
登录
职称英语
The Earth comprises three principal layers: the dense, iron-rich core, the m
The Earth comprises three principal layers: the dense, iron-rich core, the m
游客
2024-01-29
58
管理
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. [br] 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://tihaiku.com/zcyy/3405188.html
相关试题推荐
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
[originaltext](3)TennisplayersmustwearalmostallwhiteatWimbledon.T
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
Howdowegetmorepeopletoincreasetheirconsumptionofiron-richfoods?M
Howdowegetmorepeopletoincreasetheirconsumptionofiron-richfoods?M
Howdowegetmorepeopletoincreasetheirconsumptionofiron-richfoods?M
Howdowegetmorepeopletoincreasetheirconsumptionofiron-richfoods?M
随机试题
Today,theTowerofLondonisoneofthemostpopulartourist【C1】______anda
[originaltext]M:DidItellyouaboutmytriptoSweden?W:No,Idon’tthinks
[originaltext]M:Wehaveafewspecialsonthemenuthisevening.W:Whichone
2012年,当每个中国人都在讨论《舌尖上的中国》里各式______的美食时,“据
电路如图所示,二极管为同一型号的理想元件,电阻R=4kΩ,电位uA=1V,uB=
视网膜上仅有视锥细胞的部位是 A.视盘B.视盘的周边部C.中央凹 D.中
在四大洋中,跨经度最多的大洋是()。 A.太平洋 B.北冰洋 C.大西洋
患者女,27岁,冠折2/3,已做完善根管治疗,咬合关系正常。以下哪种修复方案较恰
为了解决股东与经营者的利益冲突,通常采取的解决方式不包括()。A.解聘 B.
某市娱乐中心发生火灾事故,事故当时造成2人死亡,23人重伤。重伤者经过6天抢救有
最新回复
(
0
)