短语词组短語Crossing Off A Concern 刪去一個問題crossing detection is off 隧道檢測是關閉;穿越檢測已關閉;交叉檢測是關閉digit -crossing off test 劃字測試zero crossing time pick -off 零點交叉時間選域zero -crossing current switching-on-off 零電流投切 返回 crossing off