Moderate difficulty and comprehensive knowledge. The physical difficulty of the whole exercise book is moderate, including both basic questions and improvement questions. The basic question type is mainly to help students consolidate what they have learned in class, and the improved question type is to guide students to deeply understand and apply physics knowledge. This difficulty design can not only satisfy students' mastery of basic knowledge, but also stimulate students' thinking and exploration. Moreover, it integrates junior high school physics textbooks, focusing on mechanical movement, mechanical principle, decomposition and synthesis of force, simple machinery, reflection and refraction of sound and light, electricity and magnetism.