短语词组短語Single Phase Unidirectional Transducer 單相單曏換能器;換能器;單曏換能器;相單曏換能器natural single phase unidirectional transducer 自然單相單曏換能器employing soingle -phase unidirectional transducer 單相單曏換能器 返回 unidirectional transducer