In animals,respiration is a physiological process by which O₂ enters the internal environment and CO₂ leaves by diffusing across a thin,moist __________.

Question

In animals,respiration is a physiological process by which O2 enters the internal environment and CO2 leaves by diffusing across a thin,moist __________.

In animals,respiration is a physiological process by which O₂ enters the internal environment and CO₂ leaves by diffusing across a thin,moist __________.