文[1]给出了圆锥曲线的一条美妙性质,本文给出更为一般的情形.定理过圆锥曲线准线上一点作该曲线的两切线,两切点所在直线过相应的焦点(其中双曲线准线上的点应在两渐近线之间).已知椭圆x2a2+y2b2=1(ab0),其左准线为l,过l上任意一点P作椭圆的两切线,切点分别为M、N,则直线MN The paper [1] gives a wonderful property of the conic curve. This paper gives a more general case. The theorem passes the two tangents of the curve over a point on the line of the conic curve. The point on the curve alignment line should be between two asymptotes. The known ellipse x2a2+y2b2=1(ab0), its left guideline is l, and any point over lp makes two tangents to the ellipse, the cut points are respectively M, N, the straight line MN