Many teachers believe that the responsibilities for learning lie with the students. 16__ a long reading assignment is given, instructors expect students to be familiar with 17 (inform) in the reading even if they do not discuss it in class or take an examination. The ideal student is considered to be one who is motivated to learn for the sake of learning, not one interested only in getting high grades. Sometimes homework is returned 18 brief written comments(评语) but without a grade. Even if a grade is not given, the student is responsible for _____19_______(learn) the material assigned. When research 20 (assign), the professor expects the student to take it actively and to complete it with minimum guidance. It is the student' s responsibility to find books, magazines and articles in the library. Professors do not have the time to explain 21 a university library works; they expect students, especially graduate students, 22 (be) able to exhaust the references in the library. Professors will help students who need it, but prefer that their students should not be too dependent on them