symmetrical DFD对称差分symmetricaladj.对称的symmetrical breaking current对称断路电流symmetrical linear structure对称直线结构symmetrical triangle pattern对称三角形趋势图symmetrical tensor operation对称张量运算symmetrical banded structure对称带状构造symmetrical terminal voltage对移端电压symmetrical band pass filter对称带通滤波器symmetrical two port network对称四端网络symmetrical electric circuit对称性电路symmetrical polyphase system对称多相制