Q$1[5$pt$]$: Report the names of the professor whose office phone numbers end with $21.$

Q$2[5$pt$]$: Report the names of the professors who supervise more than $2$ students.$$Use$$Inner Join$$method$.$

Q$3[5$pt$]$: Report the number of students who entered in the same year, and the total number of students at the last row.

Q$4[6$pt$]$: Report the department with the least number of professors, and the number of professors.