The back is entirely flat, made of either glass (more likely) or ceramic or shiny plastic in order for the cell signal to poke through.
背部全平,材质为玻璃或塑料(更像是玻璃)以保证手机信号通过。
2
The same holds true for tons of cell phones and other devices-we try to make 'em tough, but inflexible glass displays are always at risk of cracking or shattering.