按tf-idf在剔除一些常用词后给出文本中术语的统计算法和程序，并按降序进行排序,另外，对文档建立inverted file，然后进行检索的算法-Tf-idf removed by a number of commonly used words in the text given after the algorithm in terms of statistics and procedures, according to descending order, in addition, the do