classes: lecturer. difficult to understand subjects, finished studying just visualize a little about the subject, the teacher has not yet understood the subject. curriculum. difficult to understand subjects, finished studying just visualize a little about the subject, the teacher has not yet understood the subject. facility. difficult to understand subjects, finished studying just visualize a little about the subject, the teacher has not yet understood the subject. general. difficult to understand subjects, finished studying just visualize a little about the subject, the teacher has not yet understood the subject.