【单选题】一名老师可以承担多门课程,但是每门课只由一名老师讲授,每个学生可以选修多门课程,每门课程也可以被多名学生选修,学生选修课程需要记录成绩(grade)。学生(student)的信息有:学号(Sno) ,姓名(Sname) ,性别(Ssex) ,系(Sdept),年级(Syear);课程(course)的信息有:课号(Cno),课名(Cname),学时(Chour),学分(Ccredit);教师(te...
A.
student ( Sno , Sname, Ssex, Syear, Sdept) teacher( Tno , Tname, Tsex, Tzc, Tzw) course ( Cno , Cname, Ccredit, Chour, Tno) SC ( Cno, Sno, Grade)
B.
student ( Sno , Sname, Ssex, Syear, Sdept) course ( Cno , Cname, Ccredit, Chour, Tno) teacher( Tno , Tname, Tsex, Tzc, Tzw) SC ( Cno, Sno, Grade)
C.
student ( Sno , Sname, Ssex, Syear, Sdept) course ( Cno , Cname, Ccredit, Chour, Tno) SC ( Cno, Sno, Grade) teacher( Tno , Tname, Tsex, Tzc, Tzw)
D.
teacher( Tno , Tname, Tsex, Tzc, Tzw) student ( Sno , Sname, Ssex, Syear, Sdept) SC ( Cno, Sno, Grade) course ( Cno , Cname, Ccredit, Chour, Tno)