请教阅读36套第11套的11题，急~~~~马上考试了~~~

海小豹

看了各路解释，还是不明白为什么11题选B。
我对原文定位句的理解是：构成volcanic rock的material和构成
midocean ridge system的material根本不一样，再看B选项说：构成volcanic rocks的material和构成
volcanic rock的material是它俩来源层的典型代表，原文只说了构成物不一样，没表达出是典型的意思啊？
题目：11. It can be inferred from the passage that the sup-
porters of the ―layered-mantle‖ theory believe which
of the following?
□A The volcanic rocks on oceanic islands are
composed of material derived from the
lower part of the mantle.
□B The materials of which volcanic rocks on
oceanic islands and midocean ridges are
composed are typical of the layers from
which they are thought to originate.
□C The differences in composition between
volcanic rocks on oceanic islands and the
midocean ridges are a result of different
concentrations of incompatible elements
原文定位句：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 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.

竹林中人

这里是需要infer一下的，就是做下推断，要得到分层的理论，B选项必须是一个前提的。

taotao0

选择ab吧只有c不对。 b.The materials of which volcanic rocks on  oceanic islands and midocean ridges are composed are typical of the layers from which they are thought to originate. b选项其实要表达的意思就是那些materials就是各自来源于oceanic islands 和midocean ridges的那些本来的物质，没有经过其他的不相容的过程。其实就是区别于后一种理论c. 来源于 different concentrations of incompatible elements。不知道我表达清楚没有？

taotao0

如果要定位的话就是 are composed of material fundamentally different from that of the midocean ridge system.这里fundamentally对应are typical of 。

海小豹

taotao0 发表于 2013-11-21 11:43
选择ab吧只有c不对。 b.The materials of which volcanic rocks on  oceanic islands and midocean ridges  ...

不知道我这么理解对不对：就是原文的意思是说：构成volcanic rock的material 实际上来自lower mantle这一层，构成ridge的material来自upper mantle这一层，这俩material根本上不同。B选项说，构成它俩的物质具有其来源层（即upper mantle&lower mantle）的典型特征，基于materials就是来自这俩层的，那当然具备这俩层的典型特征了。
ps：依然不懂为毛fundamentally与typical对应？