GWD-TN-23某题，纠结于DE选项

orchid347

全划线的题：
Although at one time children’s programming had been limited to a few hours a week, now, however, there are at least four cable networks that dedicate themselves entirely to shows produced specifically for children.


D.    Children’s programming was once limited to a few hours a week, but now there are at least four cable networks dedicated
E.    While children’s programming had once been limited to a few hours a week, at least four cable networks are now dedicated

答案是D，可我觉得E也挺对，唯一一点就是E用了被动，难道就是这一点排除E吗~
E还有什么致命伤么~
多谢解答啊，谢谢谢谢

balapupu

过去完成时啊～没道理的呀～

chasingM7

过去完成不可以，另外原句是转折的意思，while不如but强烈

bitieming

理由跟楼上基本相同，另外补充一点，while的转折要求两边内容是同时发生的~