The sovereign debt crisis in Europe and the fiscal deficit crisis in the United States have triggered global attention on government debt. Although the overall level of fiscal deficit and debt of China's central government is within the control range, sufficient attention should be paid to various explicit and implicit local debt problems to avoid triggering public finance and financial risks. Please answer: B1.1 Why is it necessary to control government budget deficit reasonably and effectively? Please explain in detail the positive and negative effects of budget deficit on a country's economic development. (10 points) B1.2 After the outbreak of the financial crisis in 2008, many developed economies (especially the United States) adopted expansionary monetary policies while implementing fiscal stimulus plans. Please use the basic macroeconomic model to explain the reasons and effects of implementing " debt monetization". (please use IS-LM model to illustrate the influence of debt monetization on economic performance; please state the nature of the EUROPEAN financial crisis and use it as an example to state the effects of implementing debt monetization) (15 points) B1.3 The methods to reduce government debt mainly include tax financing and bond financing. What are the differences between these two methods on consumption, savings, and output (income)? (10 points)