I have a dialogue between two people on translating. I've made up my mind to use Present Perfect (
"I've forgotten") but the key says forget. I think that I am right for one simple reason: we have past event, the result having impact on the current situation (speaker hasn't money to buy what they were going to buy); it's some kind of news.
A: Oh, I've forgotten the money at home.
B: Don't worry. I'll lend you it.