对北大语料进行地名前后次的抽取，通过设置一个阈值，来控制选择。-Names of the Beijing University corpus to carry out before and after the meeting of the extraction, by setting a threshold, to control the choice.

北京大学汉语语言学研究中心下载资料（Claws词性标注算法　）-Research Center of Beijing University of Chinese linguistics downloads (Claws of-speech tagging algorithm)