Passengers prepare to board a bullet train from Chongqing North Station in southwest China's Chongqing to Taiyuan South Station in north China's Shanxi Province, Dec. 28, 2017. The 1,312-kilometer-long high-speed railway linking Chongqing and Taiyuan was officially put into operation on Thursday. Travel time between the two cities would be 9.5 hours. (Xinhua/Wang Quanchao)