Simulating standard open airway External breast compression: display device and alarm device indicator light display of correct and wrong compression ; alarm of wrong compression Intensity display of correct (at least 5cm) and wrong (less than 5cm) compression; alarm of wrong compression. Artificial respiration (inhalation): display device and alarm device Inhalation <500-600ml or > 600ml, wrong indicator light display and alarm prompting; inhalation between 500-600ml right indicator light display Indicator light display open airway