projectile line

例句：

1. 1. The projectile line is the path that an object travels through the air before it hits the ground.
   投射线是物体在空中飞行直至落地前所经过的路径。
2. 2. The trajectory of the projectile line is calculated using the formula for the parabola.
   投射线的轨迹是通过抛物线公式计算得出的。
3. 3.The projectile line was used to determine the speed and direction of the bullet.
   投射线被用来测定子弹的速度和方向。