The trachea has a number of adaptations: cartilage rings in the walls of the trachea help to keep it open ciliated epithelium and goblet cells to clean the air before it reaches the lungs Goblet ...
一些您可能无法访问的结果已被隐去。
显示无法访问的结果一些您可能无法访问的结果已被隐去。
显示无法访问的结果