用N台GPS接收机观测的同步环中，有（）条独立基线。
参考答案：N-1
单项选择。
There are many . They are watching TV. [ ]
A. womans and child
B. woman and children
C. women and children
D. women and child
A．时刻t线圈中电流的瞬时值icosωt
B．线圈中电流的有效值I
C．线圈中电流的有效值I=
D．线圈消耗的电功率P
cosωt
