5639/5640 Green Leather Slow Train, the "mountain bus", has maintained low fares during more than 20 years of operation. You can get a rare income in remote mountainous areas.\r This film reflects the humanistic care of Train 5639 by showing the deep friendship between Wu Wenzhen and other vegetable farmers and the people and things on Train 5639.\r This trip The train serves as a bridge for the Miao villagers to communicate with the outside world, and it carries the desire of the mountain villagers to live a happy life. It is not the speed that is slow, but the patience to keep pace with the low- and middle-income people.