zero curve

例句：

1. 1. The zero curve is the point where the graph crosses the x-axis.
   零曲线是图形穿过x轴的点。
2. 2. The zero curve is a mathematical concept that represents the absence of any change in a system.
   零曲线是一个数学概念，表示系统没有任何变化。
3. 3. The zero curve is used to determine the position of the center of mass in a system.
   零曲线用于确定系统中质心的位置。