For a simple example, CNKI is like a search engine like Baidu. The so-called search is search. This is a database containing many Chinese documents. If you want to use it to find the data or documents you need, you need to enter a search term, which can be title, author's name, keywords or subject words (you can choose this yourself). For example, I want to read the article "Deletion genes and tumor research progress of colorectal cancer". I can choose the title and enter "Deletion genes and tumor research progress of colorectal cancer" to get this article. If you just want to find the same type of literature, you can choose "subject words or keywords", enter "colorectal cancer", choose "and", and enter "missing genes" to find a group of articles. It's simple. Give it a try.