Wall Street dips on China, Greek worry; energy gains

U.S. stocks slipped on Monday, on the heels of disappointing Chinese economic data and increased tensions over Greek debt negotiations, though the decline was limited by another gain in oil prices. China's exports fell 3.3 percent from a year ago while imports tumbled 19.9 percent, well short of expectations, raising concerns about the health of the world's second-largest economy. "China is a negative and Greece is a negative, certainly Greece is something investors have lived wit