https://zh.toptenid.com/post/for-the-purpose-of-teaching-professor-a-of-the-university-photocopied-a-small-chapter-of-a-textbook-written-by-professor-b-note-only-23-pages-were-distributed-to-the-students-as-teaching-materials-and-it-was-noted-that-the-content-of-the-lecture-was-from-the-textbook-a-written-by-professor-b-and