The European Central Bank and the Bank of England didn't change interest rates or other measures designed to boost growth Thursday, and gave no indication that major moves are imminent.

The ECB left its key interest rate unchanged at 1%, while the U.K. central bank left its key rate at 0.5% for the eighth consecutive month and stuck to its program of buying £175 billion ($278.33 billion) in government bonds.

There are signs that the economy is starting to grow again but questions persist over how strong and sustained the apparent recovery will be. Neither the ECB nor ...