怎么有两个WINGS?

173. Since the 1930’s aircraft manufacturers have tried to build airplanes with frictionless wings, shaped so smoothly and perfectly that the air passing over them would not become turbulent.

A. wings, shaped so smoothly and perfectly

B. wings, wings so smooth and so perfectly shaped

C. wings that are shaped so smooth and perfect

D. wings, shaped in such a smooth and perfect manner

E. wings, wings having been shaped smoothly and perfectly so

这是XDF补充材料中的173题，答案是B。为什么？怎么能有两个wings呢？拜托各位NN们给予解惑。

Most of the airplanes have two wings, one left wing and one right wing.

Choice A and D are not correct because the subject of the whole sentence is aircraft manufacturers and they can not be "shaped". In Choice C, smooth and perfect can not be used to modify shaped.  Having been in Choice E makes it sound like that this action happened before some other event. But there is no such event that can be identified in the sentence.

The last one left is Choice B and it's the correct one. There is nothing wrong with the smooth because it modifies the wings.

And please modify your post subject accordingly. Thanks for your support.

Regarding how to modify the post subject, you can find more information in this link,

http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=79830&page=1

andrew斑竹解释的真是明白，多谢。