non-variant content

In this paper, we want to get the results of the research on types, causes and consequences about null content of textbook through the method of text analysis about textbooks and course st.

空无课程是指学校中应该有而没有的课程,教科书的空无内容是指教科书中应该呈现而没有呈现的知识。

The null content of a textbook means such a kind of content that should be contained in the textbook but not.

教科书的空无内容是教科书中应该呈现却没有呈现的内容。