Question: I'm 26 and want to set up a diversified portfolio for retirement. I'm almost totally invested in stocks, but I know that I should put some money into bonds. I really don't understand how they work, however, and I don't feel comfortable investing in something I don't understand. For example, I think I get the basic idea of a bond, but when I see bond yields fluctuate, I get confused. Aren't they supposed to have a consistent interest rate? --John, Portchester, New York