Passengers are seen on a train of subway line No 3 in Qingdao, east China's Shandong Province, Dec 16, 2015. The north section of Qingdao Subway Line No 3, the first subway line of Shandong, was put into operation on Dec 16. The travel time of the 12-kilometer-long line is about 19 minutes. [Photo/Xinhua]

Passengers are seen on a train of subway line No 3 in Qingdao, east China's Shandong Province, Dec 16, 2015. The north section of Qingdao Subway Line No 3, the first subway line of Shandong, was put into operation on Dec 16. The travel time of the 12-kilometer-long line is about 19 minutes. [Photo/Xinhua]