Usually I am not even using rules when I talk in English. I am copying phrases from other people.
Let's look at "I ate, and I've eaten". Which is right, and which is wrong? They're both correct. One is English, the other is American. A Russian teacher would probably disagree with the American saying, but I think they over analyze their rules too much here as well.
Let's see. I have. We're getting into our present perfect form here. We have... Eaten, ok, a past participle. I am guessing that up until this point I ate something... Right? Ok great, I guess I am finished eating something.
Let's see with I ate. Ok. We have a subject which is I. Yeap. Now ate. Ok something done in the past too. We just don't know exactly which point in the past, but who cares? When you talk to someone on the street, do you ask them the last time they used the toilet? Nope, so don't ask these type of questions. Go with the flow.
So there's the story, I wanted to show you two phrases, and how they can be both correct. If you need to over-analyze these types of rules, concentrate on bigger things like phrasal verbs!
