《辽史·本纪·卷二十九》
保大元年春正月初一，改元，赦免犯人。当初，金人举兵内侵，我国郡县丢失了将近一半。
天祚皇帝三保大元年春正月丁酉朔，改元，肆赦。初，金人兴兵，郡县所失几半。
On the first day of the first lunar month in the spring of Bao Da 1, the reign title was changed and prisoners were pardoned. At that time, the Jurchen people launched an invasion that led to the loss of about half of our country's prefectures and counties.
<s>[INST] 请提供这段文言文的现代汉语解释: 天祚皇帝三保大元年春正月丁酉朔，改元，肆赦。初，金人兴兵，郡县所失几半。 [/INST] 保大元年春正月初一，改元，赦免犯人。当初，金人举兵内侵，我国郡县丢失了将近一半。</s>
请提供这段文言文的现代汉语解释: 天祚皇帝三保大元年春正月丁酉朔，改元，肆赦。初，金人兴兵，郡县所失几半。
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保大元年春正月初一，改元，赦免犯人。当初，金人举兵内侵，我国郡县丢失了将近一半。
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