The training stage: First of all, the operators received training with respect to the theories and principles of airway management, including techniques of bag-mask ventilation, Direct laryngoscopy and tracheal intubation and light-guided and tracheal intubation until they had a good master about the theoretical background, technical risks and indications of the two techniques. Then, they had to receive manikin training of the two techniques on the Airway Management Trainer. Exposure of the glottis(EG)/tracheal intubation(TI) training would be continued before they were able to use both techniques to complete three consecutive cases of Exposure of the glottis/tracheal intubation operation successfully on the manikin trainer within 120 seconds (s) at a time.