first motion direction

例句：

1. 1.The first motion direction of the aircraft is crucial for its stability.
   飞机的首次运动方向对于其稳定性至关重要。
2. 2. During the initial motion direction, the pilot must maintain control over the plane.
   在首次运动方向时，飞行员必须控制好飞机。
3. 3. The research team focused on the first motion direction of the robotic arm.
   研究团队专注于机器人手臂的首次运动方向。