Originally Posted by
milijana
Mariusmxm explained it well, but there is one grammatical mistake made.
The verb
trebati means:
1. To need/have to/should to do something
If after verb
trebati comes another verb, then you use only form
treba (da). So the verb should always be in 3rd person of singular. If the following verb is in infinitive, then "da" is not used, if the following verb is changed trough number and person, then "da" is used.
Treba da otvorim vrata. - I
need to/have to/should open the door.
Treba otvoriti vrata. - The door should be opened.
2. To need something
If verb
trebati is followed by object, then you change it trough all faces.
I need the keys - Trebam ključeve, but we don't use the active in this case, but passive so the translation from English into Serbian would be
Trebaju mi ključevi.
Again, I hope I helped