Mathematical learning sets and their representations, relations between sets, operations, equations and inequalities, functions, series, space solid geometry, etc. The middle school stage is mainly vocational education, and the examination in the middle school stage is relatively difficult, the competition is not very fierce, and there is basically no pressure to enter a higher school. Information about secondary specialized schools: Secondary specialized schools, referred to as secondary specialized students for short, have their enrollment incorporated into the national unified recruitment plan, graduated with the employment registration certificate (formerly known as dispatch certificate) issued by the Employment Guidance Office of College Graduates of the Provincial Personnel Department, and have a complete set of personnel cadre file procedures, providing a large number of secondary specialized talents and second-level management talents for the society every year. Students mainly study secondary professional knowledge at school, and also study culture classes. It is usually carried out after the end of nine-year compulsory education, which has a progressive relationship with the professional knowledge of colleges and universities with corresponding majors. Secondary schools are divided into general secondary schools, vocational secondary schools and adult secondary schools (including staff secondary schools). Ordinary secondary schools are different from and do not include vocational high schools, vocational secondary schools and technical schools.