Answer:
He proved the universe is expanding
I’m not 100% sure if this is a scientific theory but I’m going with the big bang theory. The big bang theory is a scientist best guess on how the world came to be. A 2013 map of the background radiation left over from the Big Bang, taken by the ESA's Planck spacecraft, captured the oldest light in the universe. This information helps astronomers determine the age of the universe.
Answer:
respiratory system
Explanation:
The function of the respiratory system is to move two gases: oxygen and carbon dioxide.
Answer:
Because it usually takes a long time, and is a very long process.
Explanation: