Hey there!
Airplanes must be pressurized when flying at high altitudes so that the oxygen levels stay normal for us to breathe. The higher you go up, the thinner the air gets, which causes breathing problems for us humans.
Thank you!
Answer:
the crust because all of the cores are inside the earth towards the middle but the crust is the very earth we walk
Explanation:
<span>Some of the people who live in the Sahara raise crops on irrigated land in an oasis. Others tend flocks of goats, sheep, and camels. These herders find grass for the stock along the desert's fringe or where sudden rains have fallen. They live in tents so they can move easily as soon as the grass is eaten in one place.</span>
