The human cardiovascular system is considered closed because
a. blood is continuously circulated in the body.
b. blood provides nutrients to organs.
c. blood collects oxygen from the lungs
d. there are no holes for blood to enter or leave the system

Melissa lives in a town called greendale. she discovers that when she lights a match and holds it near her kitchen faucet, the little flame grows into a larger fire. melissa is surprised because she thought the water would extinguish the flame rather than ignite it further. her mother tells her that the water might be contaminated with dissolved methane, a primary component in natural gas. melissa investigates the matter and finds that cases of methane contamination started shortly after a company began fracking for natural gas in the area. based on this information, which three statements are plausible consequences of fracking in greendale?

Why are common names a problem for scientist?

Where is pericardial fulid located