Train crew members attend etiquette training in Yinchuan, northwest China''s Ningxia Hui Autonomous Region, Dec. 11, 2020. The Yinchuan-Xi''an high-speed railway is about to be put into service. Train crew employees of Yinchuan passenger section of China Railway Lanzhou Group Co., Ltd. are getting ready for the operation of the rail line. (Xinhua/Chen Bin)

Train crew members learn professional knowledge in Yinchuan, northwest China''s Ningxia Hui Autonomous Region, Dec. 11, 2020. The Yinchuan-Xi''an high-speed railway is about to be put into service. Train crew employees of Yinchuan passenger section of China Railway Lanzhou Group Co., Ltd. are getting ready for the operation of the rail line. (Xinhua/Chen Bin)

Train crew members attend a training in Yinchuan, northwest China''s Ningxia Hui Autonomous Region, Dec. 11, 2020. The Yinchuan-Xi''an high-speed railway is about to be put into service. Train crew employees of Yinchuan passenger section of China Railway Lanzhou Group Co., Ltd. are getting ready for the operation of the rail line. (Xinhua/Chen Bin)

Train crew members attend etiquette training in Yinchuan, northwest China''s Ningxia Hui Autonomous Region, Dec. 11, 2020. The Yinchuan-Xi''an high-speed railway is about to be put into service. Train crew employees of Yinchuan passenger section of China Railway Lanzhou Group Co., Ltd. are getting ready for the operation of the rail line. (Xinhua/Feng Kaihua)

Train crew members attend a training in Yinchuan, northwest China''s Ningxia Hui Autonomous Region, Dec. 11, 2020. The Yinchuan-Xi''an high-speed railway is about to be put into service. Train crew employees of Yinchuan passenger section of China Railway Lanzhou Group Co., Ltd. are getting ready for the operation of the rail line. (Xinhua/Feng Kaihua)