Based on the geometry characteristics of Bertrand surfaces, the complicated surface conjugation issue can be discussed with their directrix line. 基於白川德曲面的幾何特徵，將複雜的曲面共軛問題歸結到準線上來討論。
The surface generated by a straight line,the generator,passing through a fixed point,the vertex,and moving along a fixed curve,the directrix. 錐面由一條直線，即母線，通過一固定點，即頂點，沿一給定曲線，即準線，連續移動而產生的平面。
Based on the geometry characteristics of Bertrand surfaces, the complicated surface conjugation issue can be discussed with their directrix line. 基於白川德曲面的幾何特徵，將複雜的曲面共軛問題歸結到準線上來討論。
The surface generated by a straight line,the generator,passing through a fixed point,the vertex,and moving along a fixed curve,the directrix. 錐面由一條直線，即母線，通過一固定點，即頂點，沿一給定曲線，即準線，連續移動而產生的平面。
