设有学生关系表Student(Sno#，Sname，Ssex，Sage）和选修关系表SC(Sno#, Cname#, Grade)，其中Sno为学号，Sname为学生姓名，Ssex为学生性别，Sage为学生年龄，Cname为课程名，Grade为选修成绩。基于这两个关系表，完成下列6道题目，写出相应的SQL语句。若要创建SC表，下列选项中最合适的SQL语句为________。
A. create table SC(Sno varchar(12), Cname varchar(20), Grade char(5), constraint sc_student_fk foreign key(Sno);
B. create table SC(Sno varchar(10), Cname varchar(10), Grade char(5), foreign key(Sno) references Student(Sno);
C. create table SC(Sno varchar(10), Cname varchar(10), Grade Numeric(5,2), constraint sc_student_fk foreign key(Sno) references Student(Sno);
D. create table SC(Sno varchar(10), Cname varchar(10), Grade Numeric(5,2), constraint sc_student_fk foreign key(Sno);
在Student关系表中插入一条男生记录，其学号为201841840025，姓名为李明，今年21岁。下列选项中最合适的SQL语句为________。
A. insert into Student values( 201841840025, 李明, 男, 21);
B. insert into Student values( '201841840025', '李明',21);
C. insert into Student(Sno, Sname, Sage) values( '201841840025', '李明',21);
D. insert into Student values( '201841840025', '李明', '男', 21);
将所有女生的选课成绩提高5%，下列选项中最合适的SQL语句为________。
A. update SC set Grade = Grade*1.05 where Ssex = '女'；
B. update SC, Student S set Grade = Grade*1.05 where SC.Sno =S.Sno and Ssex = '女'；
C. update SC set Grade = Grade*1.05 where Sno in (select Sno from Student where Ssex = '女')；
D. update SC set Grade = Grade*1.05 where Sno = (select Sno from Student where Ssex = '女')；
将SC表中所有选修了"Maths"课程，但成绩低于该课程平均分的选课记录全部删除，下列选项中最合适的SQL语句为________。
A. delete from SC where Grade<(select AVG(Grade) from SC where Cname = 'Maths');
B. delete from SC whereCname = 'Maths' and Grade<(select AVG(Grade) from SC);
C. delete from SC whereCname = 'Maths' and Grade<(select AVG(Grade) from SC where Cname = 'Maths');
D. delete from SC where Cname = 'Maths' and Grade < AVG(Grade);
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