Conocer
Conocí = I met
Conocía = I knew
Saber
Supe = I found out
Sabía = I knew
Querer
Quise = I tried
Quería = I wanted
No querer
No quise = I refused
No quería = I didn’t want
Poder
Pude = I managed to
Podía = I was able to
No poder
No pude = I couldn’t (and didn’t)
No podía = I couldn’t (but may have tried)
Tener
Tuve = I got/received
Tenía = I had
Tener que
Tuve que = I had to (and did)
Tenía que = I had to (but unsure if I did)
Haber
Hubo = There was (an event)
Había = There was/were (description)