Step 1 to form (regular)
begin with infinitive
Step 2 to form (regular)
add endings: ía, ías, ía, íamos, ían
Step 1 to form (irregulars)
Start with preterit stem
Step 2 to form (irregulars)
add same endings
Used as the second part (after que)
in subjunctive sentences (when it was something that did happen)