WASHINGTON (AP) — Federal Reserve Chair Janet Yellen will address Congress on Wednesday at a time of deepening uncertainty about the Fed's interest rate policies. Since the Fed raised rates from record lows in December, the economic landscape has become clouded by falling stock markets, global weakness and sharply lower energy prices. Against that backdrop, lawmakers will likely want to question Yellen about the probable pace of further rate hikes and the Fed's role in supporting the U.S.