U.S. Secretary of Treasury Jacob Lew speaks at the G20 Hangzhou summit preview event held by the Brookings Institute in Washington D.C., the United States, Aug. 31, 2016. Lew said on Wednesday that China's current RMB exchange rate fluctuations reflect market forces, pointing to the G20 forums as important mechanism to foster global commitments. (Xinhua/Yin Bogu)