og-170 对于平行结构的疑惑！

Although early soap operas were first aired on evening radio in the 1920's, they had moved to the daytime hours of the 1930's when the evening schedule became crowded with comedians and variety shows.

(A)  were first aired on evening radio in the 1920's, they had moved to the daytime hours of the 1930's

(B)   were first aired on evening radio in the 1920's, they were moved to the daytime hours in the 1930's

(C)  were aired first on evening radio in the 1920's, moving to the daytime hours in the 1930's

(D)  were aired first in the evening on 1920's radio, they moved to the daytime hours of the 1930's

(E)   aired on evening radio first in the 1920's, they were moved to the 1930's in the daytime hours

og说除了a，其他都违背了平行结构，可是为什么although引导的从句会算是平行啊？

不理解，请教大家！谢谢！

这题不是选B么？？

Choice B is the best answer. It maintains the passive voice and the past tense (were ... aired) established in the introductory clause. Choice D breaks this parallelism by shifting from passive to active voice (moved). Choice A also uses the active voice and inappropriately shifts to the past perfect tense (had moved); the past perfect should be used to indicate action completed before, not after, the action of were aired. In C, moving introduces a dangling participial phrase in place of an independent clause, thus producing a fragment. E drops were before aired and finishes the sentence with two prepositional phrases that distort the meaning.

The point  is not "although."

The points are " in the 19xx's".