Teachers' educational ability includes pedagogy, psychology and comprehensive quality. The word "teacher" has two meanings, which refers to both a social role and the undertaker of this role. Teachers in a broad sense refer to those who impart knowledge and experience, while teachers in a narrow sense refer to those who have received special education and training and are engaged in education and teaching in education (schools). Professionals engaged in education and teaching. Undertaking the mission of teaching and educating people, cultivating builders and successors of socialist cause and improving national quality —— Excerpted from People's Republic of China (PRC) Teachers Law) PCK is a teacher's unique teaching experience, a special fusion of teachers' unique subject content and pedagogy, and a concrete form of teachers' understanding of their own profession. Schulman's view regards PCK as the most useful knowledge for teachers, which can distinguish teachers from subject experts and is the most effective analogy, elaboration, demonstration and explanation. [3] In short, Schulman's definition of PCK is actually the synthesis of PCK as a variety of knowledge, including teachers' knowledge of learners, curriculum knowledge, teaching situation knowledge and teaching methods knowledge. It means "using the combination of professional subject knowledge and pedagogy knowledge to understand how the teaching of specific units is organized and presented to meet students' different interests and abilities". Grossman defines PCK as "knowledge about the teaching purpose of a subject, knowledge about students' understanding and misunderstanding of a subject, knowledge about courses and teaching materials, teaching strategies and presentation knowledge of a specific topic". [2][3]PCK is the abbreviation of subject teaching content knowledge. Teachers must master the specific knowledge of the subjects they teach: facts, concepts, laws, principles, etc. , you should also have the knowledge to transform your subject knowledge into a representation form that students can easily understand. What three words? . .