The Sensex at the Bombay Stock Exchange fell 31 points, or 0.2 per cent, to 20,072 in early trade, this morning, on investor caution ahead of the Reserve Bank's monetary policy review. Later, after the RBI cut the repo rate and the CRR, the Sensex gained ground for some time, before relinquishing all its gains, to stand 71 points, or 0.4 percent in negative territory, at 20,032 in afternoon trade, a short while ago.Key stock indices in Japan, China, Taiwan, Indonesia, Hong Kong, and South Korea had gained between 0.1 percent and 1 percent, today. But the US Dow Jones Industrial Average had ended 0.1 per cent lower in yesterday's trade.