
 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 
