简答题现有4个文档： 文档1：I know. 文档2：You know. 文档3：I know that you know. 文档4：I know that you know that I know. 试计算，文档3中的that的TF值 A、0.3 B、0.25 C、0.2 D、0.5简答题现有4个文档： 文档1：I know. 文档2：You know. 文档3：I know that you know. 文档4：I know that you know that I know. 试计算单词know的IDF值 A、0 B、ln2 C、ln3 D、ln(4/3)多选题A、 B、 C、 D、简答题现有4个文档： 文档1：I know. 文档2：You know. 文档3：I know that you know. 文档4：I know that you know that I know. 试计算，文档3中的that的TF-IDF值 A、0.2ln(3) B、0.2ln(2) C、0.3ln(2) D、0.3ln(3)