professor patty is very distraught that three students in her class cannot afford to buy the 42- chapter book for the course. the book is used for two semesters, although not all students take the second semester. she finally tells the three students that she will make copies of the first 21 chapters for them, at no charge. professor patty makes the copies and gives each chapter to the students prior to her coverage of the relevant chapter in class. if professor patty is sued for copyright infringement