光脉冲沿光纤传输由于（）而被展宽。
A.脉宽
B.损耗
C.色散
D.折射
参考答案：C
— It's seven o'clock already.I must be leaving now.
— OK.________. [ ]
A. Go slowly
B. Stay longer
C. See you
D. Take it easy
无线电广播有何特点？
