— How can they inform Audrey of their project?

— _____ they had her email address.

 [ ]

A. What if

B. Only if

C. If only

D. Now that

对于教学数据库的三个基本表S(S#，SNAME，AGE，SEX)，SLLS#，C#，GRADE)，C(C#， CNAME，TEACHER)。现根据查询条件填充下面SQL语句空白的部分。 1．检索LIU老师所授课程的课程号和课程名。 2．检索至少选修LIU老师所授课程中一门课程的女学生姓名。 3．检索WANG同学不学的课程的课程名。 4．检索全部学生都选修的课程的课程号与课程名。 5．检索选修课程包含LIU老师所授课程的学生学号。 [说明] 1．SELECT (1) FROM C WHERE TEACHER=’LIU’ 2. SELECT S. SNAME FROM S,SC WHERE S.S#=SC.S#AND S. SEX=’F’AND SC.C#= (2) (SELECTC# FROM C WHERE TEACHER = ’LIU’) 3. SELECT CNAME FROM C wHEREc#＜ ＞ (3) (SELECTSC. C# FROM S,SCWHERE S.S#=SC.S#AND S. SNAME=’ WANG’) 4. 由题知，该问题是在表C中找课程号和课程名，要求这门课被全部学生所选。 SELECT C#,CNAME FROM C WHERE NOT EXISTS (SELECT * FRoM S WHERE NOT EXISTS (SELECT * FROM S WHERE NOT EXISTS (SELECT * FROM SC WHERE (4) 5. SELECT DISTINCT S# FROM SC WHERE (5) (SELECT C# FROM C WHERE TEACHER = ’LIU’