《数学通报》2 0 0 0年第 1 1期文 [1 ]介绍一类定向问题 ,很有启发 ,但只限于某些标准方程 .笔者通过曲线系的研究可对这类问题给出更为一般的结论和证明 ,方法简捷明快 ,特介绍如下 .命题 1　常态二次曲线　Φ :Ａｘ2 +Ｃｙ2 +Ｄｘ+Ｅｙ =0 ( )过原点作斜率互为相反数的两条 The first issue of the “Medical Bulletin” 2000 paper [1] introduces a class of orientation problems and is very inspiring, but it is limited to some standard equations. The authors can give more insights on such problems through the study of the curve system. General conclusions and proofs, methods are simple and straightforward, and are introduced as follows. Proposition 1 Normal quadratic curve Φ :Ax2 +Cy2 +Dx+Ey =0 () Two points opposite to each other as slopes