Consider the following relations:

Student$($sid: integer, sname: string, major: string, level: string, age: integer$)$

Class$($cid: string, meet$\_$at: string, room: string, fid: integer$)$

Enrolled$($sid: integer, cid: string$)$

Faculty$($fid: integer, fname: string$)$

The meaning of these relations is straightforward. For example, Enrolled has one record per

student$-$class pair such that the student is enrolled in the class; each class is taught by a faculty

member $($identified by fid$).$

$6.$ Find the ids of the students who are enrolled in both COMP$2016$ and COMP$2017.$

$7.$ Find the names of the students who are enrolled in both COMP$2016$ and COMP$2017.$

$8.$ Find the ids of the students who are not enrolled in COMP$2016.$

$9.$ Find the names of the students who are not enrolled in any class.

$10.$ Find the ids of the students who are enrolled in more than one class.