I know there are several rules when to use past simple or present perfect. for example specific words like :ago,yesterday,since,for,yet etc and in such cases is simple for me what tense to use but there are also other rules for example unspecific time and in this case we have to use Present Perfect
1) "Look,I have bought a new car"
but on other hand there is a rule for past simple - finished action.So if I say:
2) "Look,I bought a new car" - would it be incorrect?
If I dont say when I bought the car do I always have to use the Present Perfect even the action is finished? This two rules make me confused cause the action seems to be finished for me but without specific time and I dont know which tense to use