中文(繁體):Can you simultaneously inhale and exhale? As we exhale, our lungs empty. As we inhale, fresh oxygenated air enters our lungs. As flying is an energy-intensive activity, birds need a highly efficient form of respiration. Their well-developed respiratory system consists of two sets of air sacs connected to bronchi. No matter if inhaling or exhaling, fresh air enters the lungs where gas exchange takes place. This unique form of respiration is referred to as "double respiration".