精选优质文档-倾情为你奉上总分一二三四五六七 密封线学院班级学号姓名东北大学考试试卷(B 卷) 学年第 学期 课程名称:数据库原理A. If R has any descriptive attribute it can be moved to E1.B. The primary key of R is the primary key of E2.C. E1 can be a weak entity setD. E2 must totally participate in R8) In the following statements about weak entity set, (_c_) is inco