方向舵是一个被固定在垂直安定面上的可移动的翼面，它用于偏航控制。
A The rudder is a replaceable airfoil which is mounted to the vertical fin and is used for yaw control.
B The rudder is a removable wing which is fixed to the vertical stabilizer and is used for pitch control.
C The rudder is a removable airfoil which is attached to the vertical stabilizer and is used for yaw control.