Clerical sexual abuse is a dramatic reality and the Catholic Church cannot let its guard down despite the progress made, Italian Bishops' Conference (CEI) chief Cardinal Matteo Zuppi said opening the CEI annual assembly at Assisi Monday.     "Thinking of a wounded world, we cannot fail to mention the dramatic reality of abuse, about which we must remain vigilant," he said.     "Some of the journey has been completed and challenges remain," he added.     "We've come a long way in recent years,