1. An increase in the sale of new houses is often a sign that an economic expansion is coming. Why would this be the case? Your response should be at least 75 words in length. 2. Explain why the aggregate demand curve slopes down. 3. How is the U.S. national economy different from those of other nations? 4. What impact did the Great Depression have on the way government set policy? 5. Why is it difficult to test macroeconomic theories? Instructions: I need all 5 of these questions answered separately. Each answer must be at least 75 words long. It doesnt have to be too overboard as long as it answers the question. The book being used is ECON Macro 3 by William A. McEachern. The deadline for the assignment is actually Tuesday night by 1am but I am willing to take the 10 point deduction for it being late if I can still get a good grade.