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$).$

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

$11.$ Find the ids of the students who are enrolled in more than two classes.

$12.$ Find the names of the students who are enrolled in more than one class.

$13.$ Find the names of the students who are enrolled in two classes that meet at the same time.

$14.$ Find the ids of the students who are enrolled in all classes.

$15.$ Find the names of the students who are enrolled in all classes taught by iTeach.