There are two states of matter that are considered fluids. what are they, and why are they considered fluids (what can they do that solids can't do)?

the answer is :

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.