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:
upper portion of the mantle crust
the outer layer of the earth
it has the atmosphere above it
it has the asthenosphere below it
it can move
it is crispy and brittle - can break easily
it has rocks and minerals
Explanation:
earth science study
Austria-Hungary was a nation of many different nationalities. If each ethnic group became an independent nation, there would be no more Austria-Hungary. Therefore, the nationalists were a threat to Austria-Hungary because if they took action, the empire would fall apart.
