Whereas lines of competition are clearly defined in the more established industries, in the Internet industry they are blurred and indistinct, as companies that compete one day may be partners the next.

1. Whereas lines of competition are clearly defined in the more established industries, in the Internet industry[MSOffice1]  they are blurred and indistinct, as companies that compete[MSOffice2] 
2. Although the lines of competition are clearly defined in industries that are more established[MSOffice3] , they are blurred and indistinct in the Internet industry, as competing companies
3. The lines of competition are clearly defined in the more established industries, unlike the Internet where they are blurred and indistinct, as companies that compete
4. Unlike more established industries, where the lines of competition are clearly defined, they are burred and indistinct in the Internet industry, as companies that compete
5. Unlike more established industries, with clearly defined lines of competition, those of the Internet industry are blurred and indistinct, as competing companies

   Answer:

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more+adj+n,你说这个more 修饰谁呢，是adj 还是n？所以有歧义，比

如：more effecient small cars应该改为：small cars that are more

efficient.

谢谢楼上的回答,

这个我也看到讨论帖说过这个问题,难道说所有的用more的比较级都不能修饰可数名词?这个恐怕不能作为标准吧

但是再看B,competing这个词在句子中明显就破坏了句子的平衡,而且,one day修饰什么呢?