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 mid-ocean ridge system， whose source，most geologists contend，is the upper mantle. 4 y) O2 D" l* i" I* w# \1 u 对于地幔分层论点来说，最好的证据乃这样一个确认的事实，即在那些海洋岛屿——这些岛屿据信是源于由下层地幔升上来的地幔柱状溶岩流(mantle plume)——上发现的火山岩石，是由与海洋中部山脊系统的物质根本不同的物质构成的，而这一海洋中部山脊系统的成因，大多数地质学家论辩道，为上部地幔。 2 b! k7 `7 A( l 难句类型：复杂修饰、插入语 # s- V) r% k% ?+ R/ }$ K 解释：本句前面的主干并不算难，即the evidence is the fact that，难就难在fact之后说明fact 的同位语从句。此从句中既有大段插入语，又有从句，较为难读。同位语从句的主语是volcanic rocks，主语后面的found on oceanic islands是分词修饰volcanic rocks的;islands后面又有一个说明islands的同位语islands believed to result from mantle plumes arising from the lower mantle，此同位语实际起到一个分隔主谓的同位语的作用。其后是谓语动词are composed/of fundamentally different from that of the midocean ridge system， whose source， most geologists contend， is the upper mantle. , T: z) ^2 e4 R2 Y% M+ h
句中有一些专有词汇。如果抛开文章不说，单看这一个句子，则句首的layered mantle thesis就难以理解。但是如果读者能够读懂句子的大致意思，看到layered mantle thesisr最有力证据就是其材料fundamentally different from… the upper mantle，这应该可以推测出，既然不同于上层地幔，则这个理论一定是在说地幔有不同的层面。 - T6 w0 [* H# P7 h 意群训练：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 mid-ocean ridge system， whose source，most geologists contend，is the upper mantle.
发表于 2012-8-15 13:05:25
