Double walls
Chinese idiom, Pinyin is ch ó ngyu á NDI é Su ǒ, which means repeated walls, overlapping keys, refers to the deep palace, with strict protection. From Wang Zhaojun.
The origin of Idioms
The first act of Wang Zhaojun by Guo Moruo: "when they move from their wonderful hometown to this palace with many walls, their sorrow is already unimaginable. It's hard to know that there are more painful things for them."
Idiom usage
To be on guard is to be on guard.
Double walls
it seem as if a whole generation had passed - gé shì zhī gǎn