短語詞組短語break changeover switch contact 先閉後斷換曏開關(guān)接點(diǎn)make -before-break changeover switch contact 先閉後斷換曏開關(guān)接點(diǎn)synchronized changeover contact 同步轉(zhuǎn)換接點(diǎn) 返回 changeover contact