AIX-EN-PROVENCE France (Reuters) – The European Central Bank will keep interest rates very low for a long period of time to ensure monetary stability but euro zone governments must do their part to boost growth and cut debt, ECB policymaker Benoit Coeure said. The euro zone has a major investment deficit, said Coeure, a member of the ECB’s executive board, adding that governments must also “invest in Europe” by cooperating more closely – another condition for stability.