Answer:
Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface. Permeable walls - allow gases to pass through. Extensive blood supply - ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.
Usually the average growth cycle of eyebrows is 5 to 7 weeks, but it can be shorter or longer depending on various factors such as, your age, metabolism, and weight.
