对于教学数据库的3个基本表：S(Sno，Sname，Ssex)、SC(Sno，Cno

题目：

对于教学数据库的3个基本表：S(Sno，Sname，Ssex)、SC(Sno，Cno，Grade)、C(Cno，Cname，Teache)，其中S表为学生表，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，C
WHERE S.Sno=SC.Sno AND SC.Cno=C.Cno AND Teacher='LIU' AND Ssex='F'
B．SELECT Sname
FROM S WHERE Ssex='F' AND Sno IN
(SELECT Sno
FROM SC
WHERE Cno IN (SELECT Cno FROM C
WHERE Teacher='LIU'))
C．SELECT Sname
FROM S WHERE Ssex='F' AND EXISTS(SELECT *
FROM SC
WHERE SC.Sno=S.Sno AND EXISTS
(SELECT *
FROMC
WHERE Teacher='LIU'))
D．SELECT Sname
FROM S WHERE Ssex='F' AND EXISTS (SELECT *
FROM SC
WHERE SC.Sno=S.Sno AND EXISTS
(SELECT *
FROM C
WHERE C.Cno=SC.Cno AND Teacher='LIU'))