retracev.重描；折回；追溯retracement line后视线retrace transformer逆程变压器retrace brightening在回扫过程中的增亮retrace one's steps壅水计算retracement channel撤通道retrace one's steps to冰壅回水retrace characteristic(扫描的)回描特性,回程特性曲线retrace characteristics回描特性retraced their steps.追溯他们的足迹retrace one's past actions供回水立管