Accessing multiple partition

I have a table xyz with partitions for the last 2
years. If I want to query multiple partitions with a
single query what do I need to do. I tried,

select bla bla bla from xyz partition(APR2006),
partition(MAY2006);

and

select bla bla bla from xyz partition(APR2006,MAY2006)

but this did not work
Can what I am trying to do be done?

Do you need to select only from few partions not all?

If you write your WHERE clause to get records from them then Oracle only goes to those partions such as


select bla bla bla from xyz
where partitioncolumnvalue between partition <value1> and <value2>;