So, see, this coefficient becomes zero exactly when the line is perpendicular to the normal vector.
看到了吧，系数变为0了，当直线垂直于法向量的时候。
2
Nitrogen is the inert gases, low expansion coefficient, not easily with the environmental temperature rise for a long time, can maintain normal tire pressure, greatly reduce the flat tire.
氮气是惰性气体，膨胀系数低，不轻易随环境温度上升而上升，可较长时间维持正常胎压，大大降低爆胎几率。
3
As shown in the table, the parting coefficient is relatively low when parting skew components from normal components.