The pirated teaching AIDS are of poor quality. As long as it is carefully identified, it is not difficult to find the difference between pirated teaching AIDS and genuine teaching AIDS, which can be identified mainly from four aspects: First, using paper. The quality of paper used for genuine teaching AIDS is more particular. In order to protect students' eyesight, many people use colored paper, mostly light yellow, and pirated books use "whiteboards". Second, the printing quality is different. Genuine teaching AIDS have even ink, while pirated books are often illegible and uneven in ink color. Third, the binding is different. The binding of genuine supplementary books is flat, and the piracy is uneven. Fourth, the content is different. Genuine teaching AIDS rarely make mistakes, while pirated books make more mistakes.