在文[1]中,分别针对椭圆、双曲线、抛物线,给出其上一点作切线的一种简易方法,文[1]利用本文要介绍的引理1,借助解析几何方法,分别给出了三个定理的证明,并且指出:“抛物线只有一个顶点,可以想象另外一个顶点在无穷远点.”即所给出抛物线的作图不同于椭圆、双曲线的作图.文[1]将圆锥曲线上一点作切线的作法,分成有心圆锥曲线和无心圆锥曲线的两种做法,并没有统一揭示圆锥曲线切线作图的内在本质. In [1], a simple method of tangent to the previous point is given for ellipse, hyperbola and parabola respectively. Using [1], Lemma 1 to be introduced in this paper, Proof of the three theorems, and pointed out: “The parabola has only one vertex, you can imagine the other vertex at infinity.” That is given by the parabola mapping is different from the oval, hyperbola mapping. There are two ways to tangential the conical curve into the concentric concentric curve and the unintentional conical curve. There is no unified way to reveal the intrinsic essence of the conic curve.