《左传·襄公·襄公二十七年》
初九日，宋平公和诸侯的大夫在蒙门外结盟。
乙酉，宋公及诸侯之大夫盟于蒙门之外。
On the 9th, the Duke Ping of Song and the ministers of the vassal states formed an alliance outside the Meng Gate.
<s>[INST] Convert the following English text into Classical Chinese: On the 9th, the Duke Ping of Song and the ministers of the vassal states formed an alliance outside the Meng Gate. [/INST] 乙酉，宋公及诸侯之大夫盟于蒙门之外。</s>
Convert the following English text into Classical Chinese: On the 9th, the Duke Ping of Song and the ministers of the vassal states formed an alliance outside the Meng Gate.
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乙酉，宋公及诸侯之大夫盟于蒙门之外。
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