Why doesn't the air run out of oxygen or fill up with carbon dioxide

1. in recent lessons, you have been reading about some of the challenges and issues that the united states faces in both foreign and domestic affairs. review your notes from chapters 39–41 and make a list of these issues. make sure you review the looking to the future and charting future courses sheets from the divisions and new realities lessons. of all the challenges and issues that the united states faces, which do you believe is the most serious in terms of foreign affairs and which in terms of domestic affairs? choose one of each and write an essay that describes each issue and explains why you believe it is the most serious. there is no right or wrong answer—you will be graded, in part, on how well you make the argument that each issue you chose is the most serious. refer to the rubric and scoring instructions on the next page to see how your teacher will grade this assignment.