3 35 Suppose that there is a corpus consisting of several documents, the value of term frequency-inverse document frequency (TF-IDF) of 'hi' and 'hello' is listed below. It implies that the word 'hi' and the word 'hello' Term TF-IDF hi o hello .5 O is shown up with a relative low frequency, appears in every document O is shown up with a relative low frequency, appears in some of documents O is shown up with a relative high frequency, appears in some of documents O is shown up with a relative high frequency, appears in every document