现在常用的光缆都是（），只有非常长的（如海底光缆）系统一般采用负色散光纤。
参考答案：正色散光缆
— I she out alone at night.
— I'm afraid not. She's a brave girl. [ ]
A. dares say; daren't go
B. dare to say; daren't go
C. dared say; doesn't dare to go
D. dared say; daren't go
Y344-114型封隔器的解封压力（）MPa。
A.1.5
B.12
C.20
D.80
