I suggest you write out answers to the following questions, looking back at your book only afterward to check yourself. The questions on the exam also may ask you to apply the concepts here to particular situations.
Chapter 12: National Income Accounting and Balance of Payments
Write the national income account identity for an open economy. Define the components.
Use the above to show that national saving does not need to equal national investment.
Use the above to show the relationship between the government budget deficit and the current account deficit.
Under what conditions might a large current account deficit be justified?