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.

这道题我选了E，但看到不少选B的答案，不知道哪个对请大家发表一下看法!

持E.

其实，本题的B、D、E初看起来，似乎都有doubt on the prediction 的作用。

但是，仔细分析，结合Therefore, Light-line is one of the companies that will most benefit if new long-distance fiber-optic telecommunications networks are constructed. 应该E最好。

B: 即使仅从利润角度考虑， spend proportionately more on labor and materials仍然可能增加更多的纯利润，比如规模经济等等带来的（当然，其实没必要这样分析的）。

D.如果没有前面的许多论述和结论中的条件（如：networks of fiber-optic cable have been replacing electrical wire for transmitting telecommunications signals. 和 if new long-distance fiber-optic telecommunications networks are constructed.），则D应该能起到很好的削弱结论的作用。