Junior high school students should copy the following from essays: clear structure, effective use of language, and logical reasoning. These elements are crucial for developing strong writing skills and critical thinking abilities. According to a study by the National Council of Teachers of English (NCTE), students who analyze and imitate the structure and language of high-quality essays demonstrate improved writing proficiency and critical thinking skills. By studying essays, students learn to organize their thoughts coherently, use precise language, and construct logical arguments, which are essential skills for academic and professional success.