A.20 B.22 C.24 D.220
A.固定磁場(chǎng) B.脈沖磁場(chǎng) C.旋轉(zhuǎn)磁場(chǎng) D.永久磁場(chǎng)
A.?dāng)嗦菲?br /> B.產(chǎn)氣式負(fù)荷開(kāi)關(guān) C.隔離開(kāi)關(guān) D.壓氣式負(fù)荷開(kāi)關(guān)