16: In recent years, networks of fiber-optic cable have been replacing electrical wire for transmitting telecommunications signals. Signals running through fiber-optic cables deteriorate, and so the signals must be run through a piece of equipment called a regenerator before being transmitted father. Light-Line is the leading manufacturer of signal regenerators. Therefore, Light-line is one of the companies that will most benefit if new long-distance fiber-optic telecommunications networks are constructed.

Which of the following, if true, casts the most doubt on the prediction about light-ling’s prospects?

A: Telecommunications signals sent along electrical wires can travel much farther than signals transmitted through fiber-optic before needing to be regenerated.

B: Expanding its production of regenerators will require Light-line to spend proportionately more on labor and materials.

C: The volume of signals that a fiber-optic cable can carry is several thousand times greater than the volume that can be carried by an electrical wire of similar size.

D: There are technologies that enable telecommunications signals to be transmitted without either wire or fiber-optic cable.

E: Several manufacturers are developing regenerator technologies that will allow signals to be transmitted many times farther than at present before requiring regeneration.

答案是E，我选的是D

E选项讲的是有几个制造商生产的regenerator能够信号比现在未regeneration之前的信号传播的远好几倍（比较拗口），我觉得这个是无关比较，文中并没有说L公司生产的regenerator不能使未regeneration之前的信号远几倍。是我理解错了吗？

而D选项也不大好，因为文中的结论是如果光纤投入使用，L会是获利最多的公司之一。

就要考试了，NN们帮忙。非常感谢。

就是E，你仔细看文章最后一句， if new long-distance fiber-optic telecommunications networks are constructed。如果没有这句的话A或者D都有道理了~

应该是E。以前有讨论过。

注意结论是说，Therefore, Light-line is one of the companies that will most benefit if new long-distance fiber-optic telecommunications networks are constructed.

而D要削弱，则相当于说不需要建new long-distance fiber-optic telecommunications networks 。等于否定了假设性结论的前提，因而起不到削弱作用。

而E相当于可能要替代老的regeneration，所以紧扣题意。