OTTAWA - The Bank of Canada on Wednesday left its key interest rate unchanged as expected and said it was seeing limited evidence that higher energy prices were fueling broad-based inflation. But Governor Tiff Macklem reiterated that the bank would not hesitate to raise rates if need be to keep inflation in check. Wednesday's decision marks the fifth consecutive meeting at which the BoC has left its key policy rate at the 2.25% level, as an array of factors have complicated the economic outlook.