Complete the thought by filling in the correct word/words on the blank
1.each lung is enclosed in a double membrane called the______.it is coated by a fluid which allows the lungs to slides freely as they expand
2.food being swallowed is prevented from entering the air tube by a thin structure called the ______.
3.one of the functions of_____.
4.the trachea is divided into two tube the ____.
5.the larynx,trachea,bronchi,bronchioles,and alveoli make up the _____.