对于教学数据库的三个基本表：S(Sno，Sname，Ssex)，SC(Sno，Cno

问题：

对于教学数据库的三个基本表：S(Sno，Sname，Ssex)，SC(Sno，Cno，Grade)，C(Cno，Cname， Teacher)，其中S为学生表，SC为学生选课表，C为课程表，则对于语句：检索至少选修LIU老师所授课课程中一门课程的女生姓名，SQL语句错误的是______。

A．SELECT Sname FROM S，SC，CWHERE Sno=SSno AND SCno=Cno AND Teacher=‘LIU’AND Ssex=‘F’

B．SELECT SnameFROM S WHERE Ssex=‘F’AND Sno IN (SELECT Sno FROM SC WHERE Cno IN(SELECT Cno FROM CWHERE Teacher=‘LIU’))

C．SELECT SnameFROM S WHERE Ssex=‘F’AND EXISTS (SELECT* FROM SC WHERE SSno=Sno AND EXISTS (SELECT* FROM C WHERE Teacher=‘LIU’))

D．SELECT Sname FROM S WHERE Ssex=‘F’AND EXISTS(SELECT* FROM SC WHERE SSno=Sno AND EXISTS (SELECT* FROM C WHERE Cno=SCno AND Teacher=‘LIU’))