Explanation:
HIV attacks a specific type of immune system cell in the body. It's known as the CD4 helper cell or T cell. When HIV destroys this cell, it becomes harder for the body to fight off other infections. When HIV is left untreated, even a minor infection such as a cold can be much more severe.
Cell membrane allows some material to pass through it while on the same time it blocks other material from entering through it
Esa canción la conozco jaja
It's biohazard. Also if it's flammable the symbol will show a flame and if it's corrosive it'll show a image with a hand being dissolved or like a spot missing by a liquid being dropped from a tube