How did World War II (1939-1945) affect the composition of GDP according to the expenditure approach? Why would that be so? c. What does it mean, in economic terms, that the ratio of net exports to overall GDP turned from positive to negative sometime in the mid-1970s? d. Compare the evolution of gross private domestic investment and of government consumption expenditures and gross investment during the 2007-2009 recession. Do they move in the same, or in opposite directions? Why would that be so