When doing medical research with human subjects, which four limitations are unavoidable

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.

protistas excret ethanol used in the manufacture of vinegar

cuz some people don't have enough food. that's why we need more ppl to donate food to the hungry.