求翻译：明、清 之际，广行海禁，广州对外贸易一度衰落。1685年，清政府正式宣布开放海禁，在广州，漳州，宁波和云台山设置海关，以管理对外贸易。1757年，清政府为防止外人往来海防要地，独留广州一扣通商，并订立“防夷规程”，限定外商在广州的的活动范围，只准他们于每年贸易季节前来进行买卖，其余时间须离开中国或撤至澳门。是什么意思？

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On the occasion of the Ming and Qing dynasties, wide line and intercourse, Guangzhou Foreign Trade was once declining. In 1685, the Qing government formally announced the opening and intercourse, in Guangzhou, Zhangzhou, Ningbo and Cloud Taishan Customs to manage settings for external trade. In 1757

Bright, clear Time, the broad good maritime restrictions, the Guangzhou foreign trade once declined.In 1685, the Qing government official announcement opening maritime restrictions, in Guangzhou, Zhangzhou, Ningbo and the Yuntai establishment customs, managed the foreign trade.In 1757, the Qing g

Ming and Qing dynasties, broad prohibition, Guangzhou's foreign trade was declining. In 1685, the Qing Government formally announced the opening of maritime trade in Canton, Zhangzhou, set in yuntaishan, Ningbo and customs to manage foreign trade. In 1757, the Qing Government to prevent outsiders fr

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