首页
登录
职称英语
No very satisfactory account of the mechanism that caused the formation of
No very satisfactory account of the mechanism that caused the formation of
游客
2024-06-05
22
管理
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. [br] The author refers to a "conveyor belt"(L. 6, Para. 1) in order to ______.
选项
A、illustrate the effects of movements in the upper layer of the earth
B、show how temperature differences depend on the positions of the continents
C、describe the complicated motions made possible by the ocean currents
D、account for the rising currents under min-ocean ridges
答案
A
解析
在此句之前一直在讲深层地壳运动的影响,“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.”而本句的主语为“这些运动”,所以正确答案是A。
转载请注明原文地址:https://tihaiku.com/zcyy/3621180.html
相关试题推荐
[originaltext]E-mailedresumesaccountfor32percentofallsubmissionsto
[originaltext]E-mailedresumesaccountfor32percentofallsubmissionsto
Insuchachanging,complexsocietyformerlysimplesolutionstoinformation
Insuchachanging,complexsocietyformerlysimplesolutionstoinformation
Insuchachanging,complexsocietyformerlysimplesolutionstoinformation
Informationabouttigersharksisrareinbookssomostofthispaperabout
Informationabouttigersharksisrareinbookssomostofthispaperabout
Informationabouttigersharksisrareinbookssomostofthispaperabout
A、Itisfromsecond-handinformation.B、Itisfromtheargumentsaboutthecount
[audioFiles]audio_eusm_0104(20106)[/audioFiles]A、Thenumberoftheiraccounts.
随机试题
[originaltext]W:Howhasthetakeoveraffectedthecompany?M:AplantinManil
图稿印刷适性检核,包括检核原稿的()等。A.阶调状况 B.颜色偏色状况
A.错配 B.点突变 C.插入 D.重排珠蛋白生成障碍性贫血(地中海贫血)
()是指建筑工程施工质量中不符合规定要求的检验项或检验点,按其程度可分为严重缺
《乡村教师支持计划(2015—2020年)》提出,城市中小学教师晋升高级教师职称
一个全部由基因型为Aa的豌豆植株组成的种群,经过连续n代自交,获得的子代中,
上海证券交易所证券交易当日无成交的,以( )为当日收盘价。A.一周收盘价 B
有红、蓝、黄、白、紫五种颜色的皮球,分别装在五个盒子里。甲、乙、丙、丁、戌五人猜
银行承兑汇票的承兑银行,应当按照票面金额向出票人收取()的手续费。A:千分之一
石方开挖常用的爆破方法有()等。A.浅孔爆破法 B.深孔爆破法 C.洞室爆
最新回复
(
0
)