电力企业存货成本包括采购成本、订货成本、（）等。

根据短文内容，从下框A~F选项中选出能概括每段主题的最佳选项。选项中有一项为多余项。

A. Classroom participation B. Differences in American university education C. Examination system D. Competition among students E. Honest policy in students’ school work F. Students’ responsibility for learning

小题1:There is considerable variety in university classrooms in the United States. Because of diverse teaching methods and non-standardized curricula (课程), no two courses are the same. Undergraduate courses are considerable different from graduate courses. The classroom atmosphere in expensive, private universities may differ from that in community colleges， which are free and open to everyone.
小题2:Participation in the classroom is not only accepted but also expected of the student in many courses. Some professors base part of the final grade on the student’s oral participation. Although there are formal lectures during which the student has a passive role (i.e., listening and taking notes), many courses are organized around classroom discussions, student questions, and informal lectures.
小题3:Many teachers believe that the responsibility for learning lies with the student. (Courses are not designed merely for students to pass exams.) The ideal student is considered to be one who is motivated to learn for the sake of learning, not the one interested only in getting high grades.
小题4:Ideally, the teacher-student relationship at universities is characterized by trust. Thus, cheating on tests, Plagiarizing (抄袭) in written work, presenting other’s ideas as original, and turning in homework completed by someone else are all prohibited (禁止).
小题5:Relationships between students in the classroom can be cooperative or competitive. International students should not hesitate to ask for help if it is needed. in classes where such a grading curve is used, students may be reluctant to share lecture notes or information for fear that their own grades will suffer.