Not credible. It is not recommended that you buy postgraduate entrance examination materials on Taobao, because a lot of efforts have been made in postgraduate entrance examination, because it is not cost-effective to drop professional courses. One of the most reliable ways is to go to the school where you apply for the exam, find the graduate students who want to apply for the major in that school, and ask them what materials to use for the exam. Most schools have exercise books or something. I don't mean to write questions from above, but you will do professional courses on it.