List the four key points of competent communication.

How do the uv rays cause damage?   what exactly causes the skin to burn;   can you be more specific about this mechanism?   3. how do photosensitive medications increase a person's sensitivity to sunlight and therefore increase their risk of getting burned?     what kind of medications can increase photo-sensitivity, can you think of some examples?

How do nicotine and tobacco cause cancer? by decreasing blood-sugar levels by damaging or changing a cell's dna by increasing heart rate by increasing phlegm and mucous production

What is the only part of your body called that should touch the ball when setting in volleyball?