How to get past tense conjugation of the verb "to know"
Basically, if it is an ㅏ verb, then you add ㅆ어 to get past tense.
verb
알다
definition
to know
declarative past (statement) 알았어
romanization
ah-rah-ssuh
pronunciation
[ 아라써 ]
join (알 + 아 -> 알아)
vowel contraction [ㅏ ㅏ -> ㅏ] (알아 + 았 -> 알았)
join (알았 + 어 -> 알았어)
That might just be more confusing than helpful.