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
2024-02-16
55
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/3454438.html
相关试题推荐
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
Theprincipaltechniqueincurrentuseforteachingreadingattheintermedi
Althoughthetwoplayersare______inthetenniscourt,theyarereallygoodfri
Whatcausesearthquakes?Theearthisformedoflayers.Thesurfaceofthee
TheEarthcomprisesthreeprincipallayers:thedense,iron-richcore,them
随机试题
•Youwillhearfiveshortrecordings.•Foreachrecording,decidehowmu
Davidsaysthathethinksagapyearisunsuitablefor______.[br]Gapyearsbe
卫生经济学是应用经济学的基本理论和方法研究卫生领域中的A.社会现象和经济现象
下列重力式挡土墙中,属于衡重式挡土墙的是()。
针对锚具静载锚固性能试验,请回答下列问题: (3)试验过程中,关于对锚具变形的
石料冻融试验后无明显损伤,冻融后的质量损失率不大于(),强度不低于试验前的(
关于上市开放式基金(LOF)的表述,错误的是()。A.是一种本土化创新
南瓜子的用法是A.驱杀绦虫研粉,60~120g,冷开水调服,后加服槟榔协同疗效B
C各图形分别由2、2、2、3、3、(3)列小图形组成。故选C。
在客户法人治理结构评价中,对客户内部激励约束机制评价需考虑的关键因素有( )。
最新回复
(
0
)