I would say burning and combustion of fuels. hopefully that helps you.
Develop a hypothesis, make observations, analyze data, draw conclusions
Going to movies, dances, or other events in a group is a good idea for teenagers because, all of the above.
All of the options listed are positive effects towards the teenagers, which make them safe in the situation. Going out with friends does remove the expectation of sexual activity, can reveal a lot about a person, and allows others to get to know each other.
Answer:
True
Explanation:
Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.
