Mr. Jackson began to work in a middle school w_____he was twenty-three. He has worked there for forty years. At the beginning, he taught u_______English. He worked hard and was kind to his students.  He t________ care of his students and all the other teachers. All the students and teachers liked him very much.  Twenty years ago, he became headmaster and he worked much h_______. Although there are over thousands of students in the school, Mr. Jackson can remember almost all the students' n_______.