寄托家园留学论坛 › 论坛 › 寄托学术类备考版 › GRE考试综合版 › 版主和G友们帮忙一下：一篇短阅读求解，关于地幔的。

返回列表

查看: 1619|回复: 3

[问答] 版主和G友们帮忙一下：一篇短阅读求解，关于地幔的。 [复制链接]

Y.Luffy
UID: 2996786

中级会员

Rank: 4

声望: 4
寄托币: 2238
注册时间: 2011-1-22
精华: 0
帖子: 122

电梯直达

楼主

发表于 2011-8-19 21:34:20 |只看该作者 |倒序浏览

Geologists have long known that the
　　Earth's mantle is heterogeneous, but its
　　spatial arrangement remains unresolved—
　　is the mantle essentially layered or
(5) irregularly heterogeneous? The best
　　evidence for the layered-mantle thesis
　　is the well-established fact that
　　volcanic rocks found on oceanic islands,
　　islands believed to result from mantle
(10) plumes arising from the lower mantle,
　　are composed of material fundamentally
　　different from that of the midocean
　　ridge system, whose source, most
　　geologists contend, is the upper mantle.
(15) 　Some geologists, however, on the basis
　　of observations concerning mantle
　　xenoliths, argue that the mantle is
　　not layered, but that heterogeneity is
　　created by fluids rich in "incompatible
(20) elements" (elements tending toward
　　liquid rather than solid state)
　　percolating upward and transforming
　　portions of the upper mantle
　　irregularly, according to the vagaries
(25) of the fluids' pathways. We believe,
　　perhaps unimaginatively, that this
　　debate can be resolved through further
　　study, and that the underexplored
　　midocean ridge system is the key.

19. It can be inferred from the passage that thesupporters of the “layered-mantle” theory believe which of thefollowing?
I. The volcanicrocks on oceanic islands are composed of material derived from thelower part of the mantle.
II. The materials of whichvolcanic rocks on oceanic islands and midocean ridges arecomposed are typical of the layersfrom which they are thought tooriginate.
III. The differences in composition betweenvolcanic rocks on oceanic islands and the midocean ridges are aresult of different concentrations of incompatible elements.×
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III

答案中的I我理解了，II该如何理解？我把原文的句子狠读了几次还是没觉得有提到这个啊。

相关帖子 Updated by 2024.12.30

• 求解托福听力问题！TPO34-L3 Plants and Pollinators
• 问两篇机经阅读题
• 长阅读 transmission ancient Roman texts 求解
• GRE 阅读
• G 阅读材料
• V165+Q168经验
• gre阅读题，求大神指点
• 求助阅读题
• 求助90.4seismic reflection中的一道题
• GRE 阅读求解！！

回应
0

使用道具举报

苏梳眠
UID: 2717864

长老三袋

Rank: 10

声望: 4712
寄托币: 38845
注册时间: 2009-10-27
精华: 16
帖子: 5721

沙发

发表于 2011-8-19 22:15:14 |只看该作者

核心词是originate~
回到第十行左右，可以看到oceanic islands上的岩石材料来自lower mantle，而midocean ridge system上的岩石材料来自upper mantle~
检出核心词arising from 和source~

人山人海，人来人往中却兀自闪闪发亮，独一无二的你！

【2025FALL】全站祈福已开放~~来领祈福章，求offer得offer

使用道具举报

银杏叶子
UID: 2925999

初级会员

Rank: 3 Rank: 3

声望: 28
寄托币: 654
注册时间: 2010-10-10
精华: 0
帖子: 14

板凳

发表于 2011-8-19 22:16:52 |只看该作者

II选项的意思是海岛上火山岩和海脊的构成物质是由他们各自起源的地层物质构成的。即火山岩是由下层地幔的物质喷发到上层形成的，而海脊的构成物质是本来就在地幔上层的物质。这个跟原文那个well-established fact讲的是一件事。
个人见解，仅供参考。

使用道具举报

fhb881125 UID: 2635575 fhb881125 当前离线最后登录 2013-3-5 在线时间 221 小时寄托币 405 声望 21 注册时间 2009-5-2 阅读权限 5 帖子 9 精华 0 积分 366 UID 2635575 禁止发言声望 21 寄托币 405 注册时间 2009-5-2 精华 0 帖子 9 主页发消息	地板发表于 2011-8-23 01:18:46 \|只看该作者提示: 作者被禁止或删除内容自动屏蔽

	使用道具举报