Need Help : Query problem

Hi Everybody!

If I've a table like below
kk | kj | pngk | vote
----+----+------+------
01 | 01 | a | 10
01 | 01 | b | 10
01 | 01 | c | 10
01 | 02 | a | 10
01 | 02 | b | 10
01 | 03 | a | 10

How do I write a query so that I can get a result as below
[ select only a record/s with same kk and kj but different pngk.
For example here I've 3 records with same kk=01,kj=01 but diff pngk=a,b,c
and 2 records with same kk=01,kj=02 but diff pngk=a,b]

> kk | kj | pngk | vote
> ----+----+------+------
> 01 | 01 | a | 10
> 01 | 01 | b | 10
> 01 | 01 | c | 10
> 01 | 02 | a | 10
> 01 | 02 | b | 10

Thanks.