Which of the statements below does our textbook identify as the major limits to fiscal policy? (Choose one or more.) A If government spending crowds out or leads to less private spending, then the increase in AD is reduced or neutralized on net. B The economy is so large that government can rarely increase spending enough to have a large impact. C It can be difficult to time fiscal policy so that the AD curve shifts at just the right moments. D Shifting AD doesn't help much to combat real shocks