select sname, snum from student where year = 2 and snum in
(
  select snum from mark where grade < 65 and deptcode in
  (
    select deptcode from department where deptname = "computer science"
  ) having count(distinct section) > 1
)

select pnum, pname from professor where deptcode not in
(
  select deptcode fromm department where deptname = "PM"
) and pnum in
(
  select pnum from class where deptcode = "CS" and cnum = 245
) having count(distinct term) = 1