E: Several manufacturers are developing regenerator technologies that will allow signals to be transmitted many times farther than at present before requiring regeneration.
楼主选D犯了一个错误,注意题目的背景信息,是说In recent years, networks of fiber-optic cable have been replacing electrical wire for transmitting telecommunications signals,用的是现在完成时态,说明fiber-optic已经铺设了。这是本题的大前提。
选 E B 按比例投资的人力和材料增加不构成削弱,毕竟这样还是会增加毛利的。难道你还想无中生有不成?
D 已经超出了题目讨论的内容。而且这样的技术存在也不一定对LL的前景有影响。如大家知道,通讯信号可以用有线和光纤传播,也可以通过无线传播,但无线的存在不一定对LL的前景有重大影响。
E。结合原文,signals must be run through a piece of equipment called a regenerator before being transmitted farther. 如果开发出 before requiring regeneration 就可以使信号传输得更远的技术,那 regenerator 的使用需求将大大缩减,因此是对 LL 前景的 weaken