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
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional
admin
2010-07-14
28
问题
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper layer of the earth behaves as a liquid when it is subjected to small focus for long periods and that differences in temperature under oceans and continents are sufficient to produce movements in the upper layer of the earth with rising currents under the mid- ocean ridges (山脊) and sinking currents under the continents. Theoretically, these movements would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occur along the ridge. This view may be correct. It has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents.
On the other hand, the theory is unconvincing because the movements do not normally occur along lines, and it certainly does not occur along lines broken by frequent changes in direction, as the ridge is. Also, it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. An alternative theory is that the sinking part of the plate, which is denser than the hotter surroundings, pulls the rest of plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part.
Another possibility is that the sinking plate cools the neighboring mantle (地幔) and produces motion currents that move the plates. This last theory is attractive because it gives some hope of explaining the neighboring mantle and produces motion currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment (沉积物). Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled material on the upper side of the might be the cause of such deep basins. The enclosed seas are an important feature of the earth’s surface and seriously require explanation.
Which of the following, if it could be demonstrated, would most support the traditional view of ocean basin formation?
选项
A、The upper mantle of the earth behaves as a dense solid.
B、Movements usually occur along lines.
C、Sinking plates cool the surface of the earth.
D、The rising motion currents keep exact pace with them.
答案
B
解析
on the other hand说明后面的理论同第一段的地壳运动一起支持海洋盆地形成理论,而且从第二段首句"On the other hand,the theory is unconvincing because the movements do not normally occur along lines,and it certainly does not occur along lines broken by frequent changes in direction,as the ridge is
转载请注明原文地址:https://jikaoti.com/ti/b7MMFFFM
0
大学英语六级
相关试题推荐
Interestinpursuinginternationalcareershassoaredinrecentyears,enhancedbypersonnelshortagesthatarecausingcompanie
ManyAsiantouristsdarenotgotoThailandsincethetsunamiin2004becauseoftheirWhatothermethodisusedtohelpoverco
Thechiefreasonforthepopulationgrowthis______________________(与其说是出生率的上升,还不如说是死亡率的下降).
Sleepwalkingisadisordercharacterizedbywalkingorotheractivitiesapersonengagedinwhile【S1】stillasleep.Itisespe
A、ItinfluencesthesurfacetemperatureofMars.B、Itprotectslivingbeingsfromharmfulrays.C、Itkeepsaplanetfromoverhea
Theoldestandsimplestmethod,then,ofdescribingdifferencesinpersonalitywasto【B1】______peopleaccordingto【B2】______.
A、Registeringacourse.B、Closingacomputersystem.C、ApplyingforanIDcard.D、Havingapart-timejob.AWhatarethetwospea
A、Indifferent.B、Regretted.C、Excited.D、Angry.B
A、Heissurprised.B、Hefeelsveryhappy.C、Heisindifferent,D、Hefeelsveryangry.C
Poetsdieyoung—youngerthannovelists,playwrightsandotherwriters,aU.S.researchersays.Itcouldbebecausepoetsaretor
随机试题
下列哪项无腹膜覆盖
以下说法()正确。
委托监理合同变更或解除合同的通知或协议(),协议未达成之前,原合同仍然有效。
胆汁质的小丁冲动、粗心又鲁莽,黏液质的小林冷静、认真又稳重,可见小林的气质类型比小丁好。()
人工智能无所不在地潜藏、萌发、产生和应用于人们生活的各个方面和各个角落,凡有人类足迹和活动的地方,都可能出现人工智能。人工智能似乎必然会与人产生激烈的竞争,随后形成事实上出乎人的意志的结果——人工智能对人类造成威胁,并可能最终战胜人。 以下各项如果为真
算术平均收益率和几何平均收益率的差值()。
2019年4月30日,习近平在纪念五四运动100周年大会上引用鲁迅的名言指出,青年“所多的是生力,遇见深林,可以辟成平地的,遇见旷野,可以栽种树木的,遇见沙漠,可以开掘井泉的”。这表明()
A、showsthatpeopleallovertheworldcareaboutPakistanB、demonstratesearthquake’sgreatinfluenceC、doesn’tmakeanysense
ConversationalSkills1.Skilltoaskquestionsa)Beawareofthehumannature:readinesstoanswerothers’questionsregard
Thailandisabeautifuland(attract)______country.
最新回复
(
0
)