A los verbos regulares le agregas la terminación "ed"
A os verbos irregulares cambian su forma en el pasado
BUY - BOUGHT (Irregular) -comprar
SEE - SAW (Irregular) -ver
HAVE - HAD (Irregular) -tener, haber
GIVE - GAVE (Irregular) -dar
WATCH - WATCHED (Regular) -mirar tv
HIT - HIT (Irregular) -golpear
MAKE - MADE (Irregular) -hacer, fabricar, crear
THINK - THOUGHT (Irregular) -pensar, creer
Saludos:)