A.高頻段B.中頻段C.低頻段D.中高頻段
A.順時(shí)針轉(zhuǎn)過(guò)π弧度B.順時(shí)針轉(zhuǎn)過(guò)2π弧度C.逆時(shí)針轉(zhuǎn)過(guò)π弧度D.逆時(shí)針轉(zhuǎn)過(guò)2π弧度
A.0B.1C.2D.3