Because not all problems are done. Because some chapters are skipped. Because one textbook may cover 2 semesters at one university and 3 at another one - so that, say, Physics 2 only covered 2/3 of what Physics 2 covered elsewhere.
Because not all problems are done. Because some chapters are skipped. Because one textbook may cover 2 semesters at one university and 3 at another one - so that, say, Physics 2 only covered 2/3 of what Physics 2 covered elsewhere.