电力操舵装置控制系统的两套独立操舵系统是：（）
A.手柄操舵和应急操舵
B.随动操舵和手柄操舵
C.手动操舵和自动操舵
D.自动操舵和应急操舵
参考答案：B
This dictionary is _____ to me, but that one is _____ .
A．great help; helpful
B．a great help; of little use
C．important; of few importance
D．very helpful; of no any use
G.655光纤色散系数理论值为5ps/nm/km，实际我们通常采用（）。
A.5ps/nm/km
B.6ps/nm/km
C.9ps/nm/km
D.10ps/nm/km
