查询学生的学号，姓名，选修课程号和课程成绩

A.select sid，sname，cid，cname from student，course

B.select sid，sname，cid，cname from student，sc

C.select sid，sname，cid，grade from student，sc where student.sid=sc.sid

D.select * from student，sc where student.sid=sc.sid

正确答案：select sid，sname，cid，grade from student，sc where student.sid=sc.sid