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
考研
The Theory of Continental Drift has had a long and turbulent history since it was first proposed by Alfred Wegener in 1910.【F1】V
The Theory of Continental Drift has had a long and turbulent history since it was first proposed by Alfred Wegener in 1910.【F1】V
admin
2017-10-23
70
问题
The Theory of Continental Drift has had a long and turbulent history since it was first proposed by Alfred Wegener in 1910.【F1】
Vigorously challenged yet widely ignored, the theory had languished for half a century, primarily due to its lack of a plausible mechanism to support the proposed drift.
With the discovery of sea-floor spreading in the late 1950’s and early 60’s, the idea was reinvigorated. Plate tectonics is now almost universally accepted. Many details of the mechanism are to be worked out.
The surface of the Earth is divided into approximately six large plates, plus a number of smaller ones. The plates are bounded by an interconnected network of ridges, transform faults, and trenches. Ridges, also called spreading centers, occur where two plates are moving away from each other. As the plates separate, hot molten mantle material flows up to fill the void.【F2】
The increased heat resulting from this flow reduces the density of the plates, causing them to float higher, thus elevating the boundaries by many thousands of feet above the colder surrounding sea floor.
【F3】
Ridges on the ocean floor form the longest continuous ranges of mountains on the planet, but only in a very few places on the Earth do these mountains rise above the ocean surface.
New sea floor is constantly being created along spreading centers. Obviously somewhere else old sea floor must be going away. This occurs in trenches, also called subduction zones. Trenches occur along the boundary between two plates that are moving towards each other.【F4】
Where this occurs, one plate is bent downwards at about a 40°angle and plunges under the other plate’s leading edge, eventually to melt back into the liquid mantle below.
As the subducting plate is heated back up to mantle temperatures, certain minerals in the plate melt sooner than others.【F5】
Minerals that melt at lower temperatures and are lighter than the surrounding material tend to rise, melting their way up through the overriding plate to erupt as volcanoes on the ocean floor.
As these volcanoes grow, they rise above the ocean surface to form lines of islands along the leading edge of the overriding plate. Numerous islands of Micronesia and Melanesia in the western Pacific were created in this way.
【F4】
选项
答案
在海沟出现的地方,一个板块向下弯曲至40度左右的倾角插入另一个板块前缘的下面,最后熔汇于下面的流体地幔中。
解析
本句主干是one plate is bent…and plunges under…。where引导地点状语从句,主句中有两个并列谓语:is bent…和plunges under…。本句的关键是理解句子结构,找出地点状语从句和并列谓语。
转载请注明原文地址:https://kaotiyun.com/show/ccIZ777K
0
考研英语一
相关试题推荐
Scientistshavefoundthatalthoughwearepronetosnapoverreactions,ifwetakeamomentandthinkabouthowwearelikelyto
Doyourememberallthoseyearswhenscientistsarguedthatsmokingwouldkillusbutthedoubtersinsistedthatwedidn’tknow
Overthepastcentury,allkindsofunfairnessanddiscriminationhavebeencondemnedormadeillegal.Butoneinsidiousformco
Itusedtobesostraightforward.Ateamofresearchersworkingtogetherinthelaboratorywouldsubmittheresultsoftheirres
ThemostthoroughlystudiedintellectualsinthehistoryoftheNewWorldaretheministersandpoliticalleadersofseventeenth
By1830theformerSpanishandPortuguesecolonieshadbecomeindependentnations.Theroughly20million【C1】______ofthesenati
In1924America’sNationalResearchCouncilsenttwoengineerstosuperviseaseriesofexperimentsatatelephone-partsfactory
Inthissection,youareaskedtowriteanessaybasedonthefollowinginformation.Makecommentsandexpressyourownopinion.
Inthissection,youareaskedtowriteanessaybasedonthefollowinginformation.Makecommentsandexpressyourownopinion.
Inthissection,youareaskedtowriteanessaybasedonthefollowinginformation.Makecommentsandexpressyourownopinion.
随机试题
鲁迅是20世纪中国伟大的思想家、文学家。下列属于其作品的有()。
焊割场地周围()范围内,各类可燃易爆物品应清理干净。
腹膜外位器官有
A.应激B.应对C.防御D.投射E.固着引起全身适应综合征的是
亚硝酸钠加入肉制品的主要作用是
根据施工质量控制的特点,施工质量控制应()。
关于明代内阁,下列表述正确的是()。
在财产保险中,除了海洋运输货物保险的保险利益时效有一定的灵活性之外,一般要求,保险合同在()存在保险利益。
在Word的页面视图方式下,在屏幕上看到的与打印出来的文稿(文字、图片、页眉、页脚等)布局格式()。
TheBeautyAdvantage[A]MostofushaveheardthestoryofDebrahleeLorenzana,the33-year-oldQueens,N.Y.,womanwhosuedCit
最新回复
(
0
)