关于独立主格

doudouzhu

请问各位NN，能否有人讲一下独立主格。我是实在是不明白。

下面这个例子是帖子里大家认为是独立主格的。
GWD6-Q41:。

The greatest road system built[ in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador
through Peru to Southern Chile.
A.Columbus
was the Incan highway, which, over 2,500 miles long and extending
B.Columbus
was the Incan highway, over 2,500 miles in length, and extended
C.Columbus
, the Incan highway, which was over 2,500 miles in length and extended
D.Columbus
, the Incan highway, being over 2,500 miles in length, was extended
E.Columbus
, the Incan highway was over 2,500 miles long, extending
这里选E。

venus2elva

曾经也很纠结的一道题。
错选过B.

这里E确实最好，the Incan highway做了The greatest road system的同位语。原本觉得E中将句子表达的主要意思变成了 the Incan highway was over 2,500 miles long，有改变句子重心之嫌，因为原句是说The greatest road system was the Incan highway。后来看帖子才恍然大悟。这句子后面说XXX over 2500 miles long, extending  from northern Ecuador 这些表示有多长，延伸到哪里的修饰词，都只能用来修饰highway而不能是修饰The greatest road system.

所以原句想要表达的意思应该是The Incan highway, the greatest road system built[ in the Americas prior to the arrival of Christopher Columbus,was over 2,500 miles long, extending from northern Ecuador through Peru to Southern Chile.

好像有些答非所问了 = = LZ问独立主格来着。。。我是从同位语理解来着。。。