轨迹概念包含“纯粹性”与“完备性”两方面的要求.本文试图通过若干典型错例,对造成轨迹“漏”、“杂”的原因进行探讨。一、忽视特殊情形. 求轨迹时,除了对动点的运动规律作一般情形的考察外,还要重视研究动点的特殊位置,如极限位置,临界位置,轨迹与坐标轴的交点,使几何图形为极端情形的动点等.忽视对这些特殊情形的研究,常常造成轨迹“漏”、“杂”. The concept of trajectory contains the requirements of “purity” and “completeness”. This article attempts to explore the causes of trajectory “leakage” and “miscellaneous” through a number of typical mistakes. I. Ignoring special situations. When seeking trajectories, in addition to examining the motion of moving points in general, we must also study the special positions of moving points, such as extreme positions, critical positions, intersections between trajectories and coordinate axes, and geometry. The graph is the dynamic point of extreme situations. Ignoring the study of these special situations often leads to trajectory “leakage” and “miscellaneous”.