1, the space is small. The second-class seat space of the d939 is too small for proper activities. Sitting for a long time is very tiring.
2. Seats. The backrest of the d939 second-class seat is basically straight, with no radian. The design is not ergonomic and there is no waist support. The sides of the backrest are flat to the middle, so it is very tiring to sit up.