山外有山，天外有天[shān wài yǒu shān tiān wài yǒu tiān]
词典There are mountains beyond mountains, and heavens beyond heavens.
词典However perfect the things may be there may always appear better ones.
1. 天外有天，山外有山。
Behind the mountains there are people to be found.
2. 山外有山，天外有天
2. 山那边的草更绿。（山外有山，天外有天。）
The grass is greener on the other side of the hill.