Question

lungs hava millions of -
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Answer 1

Answer:

Within the lungs, the mucus-lined bronchi split like the branches of a tree into tens of thousands of ever smaller tubes (bronchioles), which connect to tiny sacs called alveoli. The average adult's lungs contain about 600 million of these spongy, air-filled structures.

Explanation:

Answer 2

Answer:

alveoli is the answer of this question