Why does your heart never tire of constantly beating to pump blood thought out your body

Frankie is having difficulty developing a friendship with histeammate curtis. whenever frankie invites curtis to hangout with him at the park, curtis always says that he's busy. what is most likely preventing a healthy relationship fromforming? a)the boys are not being generous with their time andeffort. b)the boys are not communicating. c)both boys are too busy. d)the boys are on different teams.

Cardiac output is affected by heart rate exercise stroke volume all of the above

The effects of tobacco use on society include high taxes and loss of life. select the best answer from the choices provided. t f