More to explain and take out of the dictionary.....

abandonar is the complete, spanish one form...if you wish to say it in the prederite or past tense form than this is how you say it.

For your information, yo means I, tu means you, el-ella-Ud. means he-she, nosotros means they, vosotros is they in Spain, and ellos-ellas-Uds. is them.

Ud and Uds. is Ustedes meaning a polite form of el ello ellos or ella ellas.

yo-abandone
tu-abandonaste
el,ella,Ud.- abandono
nosotros- abandonamos
vosotros- abandonasteis
ellos,ellas,Uds.- abandonaron

Present tense for this verb is:

yo-abandono
tu- abandonas
el,ella,ud.-abandona
nosotros-abandonamos
vosotros-abandonais
ellos,ellas,Uds.-abandonaron