《旧唐书·本纪·卷十七》
十二月己酉是朔日，月初一。
十二月己酉朔。
December, 21st, Jiyou, the first day of the month.
<s>[INST] Convert the following modern Chinese text into Classical Chinese: 十二月己酉是朔日，月初一。 [/INST] 十二月己酉朔。</s>
Convert the following modern Chinese text into Classical Chinese: 十二月己酉是朔日，月初一。
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十二月己酉朔。
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