Several parts of a serve include four links: preparing posture (holding the ball), throwing the ball, swinging the arm and hitting the ball into the field.
In response to your question, physical education class's theoretical test definitely refers to the forehand serve of volleyball, so the action essentials of forehand serve are: facing the net, the feet are naturally open, the left foot is in front, and the left hand holds the ball in front. Lift the ball with the plane support of the arm and palm, and throw it to the front and upper part of the right shoulder smoothly and vertically, with a moderate height. While throwing the ball with your left hand, raise your right arm, bend your elbow back to shoulder level, and turn your upper body slightly to the right. Straighten the highest point of the upper arm in front of the right shoulder and hit the back with the palm of your hand. When hitting the ball, the fingers naturally open to match the ball, and the wrist quickly makes a push to make the ball fly upwards. After hitting the ball, the center of gravity moves forward and returns to the court quickly.
Specifically, it should be the hitting action, hitting point, hand shape and strength.
The answer can be found in the examination paper.