Once Hitler took Poland, he instituted the rules; this meant Polish had to serve Germans first in restaurants and shops, and Pols had to get off the sidewalk if a German were walking there.

crop rotation kepy different plants in the soil instead of once constintly. when switching out plants you have different nutrients being absorbed at different speeds and different roots growing differently therfore the spoil and water flow have to adapt and carry fresh nutrients to carry the constant changes that were going on in the soil.

answer; i believe that the correct answer is (chronological order);

porter is writing economic history because he is focusing on the cost of developing vaccines.

studies show tha in 7.5 billion years from now, the expanding sun will engulf, and destroy, the earth.