Hong Kong stocks finished lower Tuesday as investors struggled to maintain early gains following a general advance across Asia that tracked a Wall Street surge. The Hang Seng Index dropped 0.63 percent, or 179.24 points, to 28,309.76. But the benchmark Shanghai Composite Index added 0.80 percent, or 2823 points, to 3,557.41, while the Shenzhen Composite Index on China's second exchange rose 0.51 percent, or 12.22 points, to 2,408.41. dan/je