What is the amount of fluoride concentration in water that's considered safe for the prevention of dental decay?

How is the structure of our circulatory system and respiratory system related to the function of both these systems?

What is true about the roles you have in your family?family roles only exist within a household. roles you have are the same even outside of the home. roles remain the same despite changing age. roles you have change with age, experience, and knowledge.

Ijust want the meaning to life (no wrong or right answers i just want your true opinion)