The first diagnosis is the most difficult, and the second diagnosis will be more difficult than the senior high school entrance examination. The initial test and re-test in Chengdu are more difficult than the college entrance examination, and the initial test sites cover the knowledge points of various subjects in high school and examine the comprehensive quality of students, so it is the most difficult. The second diagnosis mainly examines students' understanding ability and mastery of subject knowledge. The difficulty is slightly lower than the initial diagnosis, and the difficulty of the follow-up visit will be closer to the senior high school entrance examination. There are three diagnostic tests in junior high schools in Chengdu: zero diagnosis, one diagnosis and two diagnosis. "Zero diagnosis" refers to the unified examination at the end of Grade Two, "One diagnosis" refers to the unified examination at the end of Grade Three, and "Two diagnosis" refers to the unified examination at the end of April of Grade Three.