The human cardiovascular system is considered closed because

Ihave a really high metabolism and only weigh 70 pounds (13 almost 14). people always ask me two questions: do you ever eat and how do you eat so much and stay so skinny. i am worried that a high metabolism wont me forever. what are some safe steps i can take to maintain being fit. (also, i already work out i am a dacer so i get cardio a lot)

Recall what you know about common challenges to mental and emotional health. what are some signs or traits of individuals with low self-esteem, stress, depression, and mental disorders

Which researcher said that children learn best when given learning tasks that are right for their developmental age?