this should work for you assuming you mean hospitals that have > 2 dedicated doctors.
SQL> select * from hospital;
HID NAME COUNTRY AREA
---------- -------------------- ------------ ----------
1 General Spain 1
2 Hospital 2 Spain 1
3 Hospital 3 Spain 1
SQL> select * from doctor;
IC NAME DATE_OF_BIRTH
---------- -------------------- -------------
1 Gregory House 1
2 Dougie Howser 1
3 Marie Curie 1
4 Dr Who 1
5 Dr Zeuss 1
SQL> select * from work;
HID IC SINCE
---------- ---------- ----------
1 1 1
1 2 1
2 3 1
2 4 1
3 4 1
1 5 1
6 rows selected.
SQL> select h.hid, h.name
2 from hospital h
3 inner join work w
4 on w.hid = h.hid
5 inner join doctor d
6 on d.ic = w.ic
7 where not exists (select null
8 from work w2
9 where w2.hid != h.hid
10 and w2.ic = w.ic)
11 group by h.hid, h.name
12 having count(*) > 2;
HID NAME
---------- --------------------
1 General