og 205, although

205. The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over
them; the resulting flow pattern, with crests and troughs that remain stationary although the air that forms
them is moving rapidly, are known as "standing waves."
(A) crests and troughs that remain stationary although the air that forms them is moving rapidly, are
(B) crests and troughs that remain stationary although they are formed by rapidly moving air, are
(C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is
(D) stationary crests and troughs although the air that forms them is moving rapidly, are
(E) stationary crests and troughs although they are formed by rapidly moving air, is

ETS said that

Choice E uses the correct verb form, is, but it incorrectly introduces a dependent

adverbial although clause into a prepositional phrase (with crests ...).

I still don't know what is the mistake

这是语法规则, 介词短语里不可以跟从句.

我感觉不是介词短语里不能跟从句一棍子打死。C其实就在介词短语里面套了一个定于从句。

而是： although引导的是一个 dependent clause，也就说是他引导的是一种不能脱离主句存在的从句。

他引导状语从句修饰主句动作。

但是在E,D里面，没有主句，although找不到修饰对象了。

而C，虽然也在介词短语里面，但是这个介词短语的宾语 crest and trough后面跟了一个定语从句，这个定语从句有谓语 remain，而although又套在这个定于从句里。 光从that引导的定从句里来看， although引导的从句，对应有主句： remain stationary..

5 楼的解释非常好。

哈哈。。。如果昨晚上看这道题，就看不到这么精彩的解释了。

同谢5楼的同学.

我也一直没弄清楚这一题的解释.

a very specific explain

说的很对

其实就是：although 引导的从句必须对应从句，而不是短语，而E里边只有短语。他们都是套在介词短语(with...)里边的