《史记·七十列传·匈奴列传》
匈奴单于呆在汉朝边塞以内一个多月就离开了，汉朝兵马追出塞外就返回塞内，没能斩杀敌军。
单于留塞内月馀乃去，汉逐出塞即还，不能有所杀。
The Xiongnu Shanyu stayed inside the Han border for more than a month before leaving, the Han army pursued them out of the border and then returned to the border, failing to kill the enemy.
<s>[INST] Rewrite the following English passage in the style of Classical Chinese: The Xiongnu Shanyu stayed inside the Han border for more than a month before leaving, the Han army pursued them out of the border and then returned to the border, failing to kill the enemy. [/INST] 单于留塞内月馀乃去，汉逐出塞即还，不能有所杀。</s>
Rewrite the following English passage in the style of Classical Chinese: The Xiongnu Shanyu stayed inside the Han border for more than a month before leaving, the Han army pursued them out of the border and then returned to the border, failing to kill the enemy.
user
单于留塞内月馀乃去，汉逐出塞即还，不能有所杀。
assistant