The lungs inhale and exhale in the same manner.To inhale, your diaphragm and intercostal muscles contract , which causes the chest cavity to expand.The pressure drops and air rushes in.

• 肺吸气和呼气的原理就是这样，吸气时，横隔膜和肋间肌收缩，因此胸腔会扩张，胸腔气压变小，空气就跑进来了。