When assessing an unconscious casualty lying on the ground at an accident scene, how should the rescuer determine if the person is breathing?

1. Shake the casualty's head violently for 30 seconds
2. Observe chest rise and fall, listen for breath sounds at the mouth, and feel for exhaled airflow on the cheek for 5 to 10 seconds (一听、二看、三感觉)
3. Wait 15 minutes to see if the casualty wakes up naturally
4. Splash hot tea onto the casualty's face