《左传·定公·定公六年》
冬季，在城中筑城。
冬，城中城。
In winter, they built a wall in the city.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 冬，城中城。 [/INST] In winter, they built a wall in the city.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 冬，城中城。
user
In winter, they built a wall in the city.
assistant