This is a serious question i'm asking myself.

are black dots on skin cancerous? (it might be my birthmark)

only answer if you really know the answer.

Increased use of cocaine can reduce the period of stimulation. true or false

What is a risk associated with medicines?

Mucous membranes.. a. cover or line external surface of body. b. line internal body surfaces that are in contact with the environment. c. produce antibodies to combat infection. d. secrete sweat, which has antibacterial enzymes.