SQL & PL/SQL :: Best Way To Select Out Of Group Condition

I am asking about the best way in SQL for the following case:

CREATE TABLE TRY_A (A NUMBER, B NUMBER);

INSERT ALL
INTO TRY_A VALUES (1,0)
INTO TRY_A VALUES (1,1)
INTO TRY_A VALUES (1,2)
INTO TRY_A VALUES (2,0)
[code].......

I need to learn the best way to select all A values where B is never 0. So if the needed result for the above example is:

A
--------------
3
5

As column B was never 0 with column A = 3 or 5.