有个员工表employees，该表中有职务列。你想检查哪些员工的信息中没有填写职务一栏，应该使用（）。

A.Select unique所在省市from Student
B.Select所在省市from Student
C.Select only所在省市from Student
D.Select distinct所在省市from Student

A.select employeesno，ename Name，job from employees where ename=‘SMITH’
B.select employeesno，ename ‘Name’，job from employees where ename=SMITH
C.select employeesno，ename “Name”，job from employees where ename=‘SMITH’
D.select employeesno，ename ‘Name’，job frome mployees wheree name=‘SMITH’

A.in
B.exists
C.between
D.like