Thank you for invaluable help!!!
1. But I can't figure out a little point: Why It isn't allowed to say "It sounds unnaturally" I think that "unnaturally" is a adverb and so You can change the meaning of a verb (an expression of an action) by means of it. For example, I suppose that I can say: "I am used to do it" and "I am used to do it unnaturally" - Isn't it right. But If it's right then why I can't say "It sounds unnaturally" and can only say "It sounds unnatural"?
2. I cant comprehend the difference between "Past Simple" and "Present Perfect". For instance, can I say something like this "a meeting is going on. The main question is who does know Tom very well
for some purposes. A man answer "I have always gone to school with him so that I know him very well"" I suppose that if we have some action done and also have the result of it, which is necessary for us now, we must use the Present Perfect Tense, and if the result isnt necessary for us, if we say a phrase for no better reason than to keep up the conversation, we must use Past Simple. If I'm wrong, Please, correct my surmises