Many thanks for such an exhaustive explanation!
Of course I understand that native-speakers are free to speak as they wish, but... but Englishmen are always seemed to me extremely conservative and crazy about all kinds of rules. Well, they are only human, eh? Moreover, I can forgive him (I mean Sting) almost anything, even direct violation of grammar rules

But I think that he sings "Everything she do..." all the same!

Thank you once again

you are most welcome

ut Englishmen are always seemed to me extremely conservative and crazy about all kinds of rules.

not in the least, well, concerning the present-day natives... pretty often their grammar (ah!) is not as academic as we were taught to think they were, let alone their accents (pronouncing /studi/ instead of /stadi/ for example) , imho, of course, but from the bottom of my heart as well as my experience, some of them require good drilling

pronouncing /studi/ instead of /stadi/ for example
My world is completely destroyed.
I talked to people from various social groups... to the English, to the Scots... but I've never come across anything like that. Lucky me!
OK, I'll take it easy then. "Do" or "Does"... oh it's a small matter!.. Espessially for native-speaker. Espessially in comparison with any American comedy. I can't understand them at all.

P.S. By the way, do I make many mistakes?

Nothing to worry about, hope you world can be easily restored

probably the following links could help:

http://public.wsu.edu/~brians/errors/he_don%27t.html
http://www.englishforums.com/English/IfHeDontOrIfHeDoesnt/gznlw/post.htm
http://english.stackexchange.com/questions/4578/he-dont-or-he-doesnt

What I like about English is that this is the language of many possibilities True, they have strict rules which they compel us to learn and obey, conversely when they are too lazy to follow the same rules they call it 'various accents' Joking apart, there at least 2 sets of rules which natives are basically born with. It's practically beyond us, non-natives, to master them equally, sadly... And that's exactly what immediately tells a non-native from a native, namely our correct grammar and RP, agrh, sadly again...

One more link with an article which can typify the language in question:
http://www.lingq.com/learn/en/workdesk/item/1865990/reader/
and which leaves no hope for 'anglophones from outside Britain'

As for /studi - stadi/, that was the accent of one of my last year's teachers... Answering in advance, highly qualified, one of the best in Moscow of advanced+ level (the fact that I don't share this opinion doesn't count ) At first it was rather challenging to follow him, and what helped was the spelling of the word. However, it was not the first time I've come across such accent, when 'u' like in run, study is pronounce more like /u/ than like /\ , actually nothing of 'ah' sound at all, to be honest (hope you got the idea). Yet, I think it's nothing compared to their short vowels, which the majority of Britons do not pronounce at all By contrast Americans are much more easy to understand, imho of course. Regarding comedies, I am not a big fan of them, guess, you need to understand what they are making fun of. By the same token, to understand Russian parodists you need to be familiar with Russian lifestyle btw, have you watched any of British comedies? Do you understand them with ease?

One more point to make. I can't say I talk to people of different social groups... All my contacts are naturally with like-minded ppl.. Lucky me Guess, bus drivers don't count And you know what, everyone has his/her language style not only in terms of pronunciation but also regarding grammar structures and vocabulary. I won't go as far as to say that they speak different languages, but the diversity is noticeable.

Having said all that, do you care about mistakes? Especially when even natives err now and then
Just to help restore your world, no, there are not many mistakes in your writing (I can't assess your speech, of course)

best regards,
oops the sun is rising again

when they are too lazy to follow the same rules they call it 'various accents'
That's nice of them ^___^ I really love them for it.

Regarding American comedies... I can't say that I'm fan. Their humour is easy enough to understand, but I don't like their way of joking. And the biggest problem is their grammar. I mean completely grammar absence. They mix 2 of 3 tenses in one sentence, skip auxiliary verbs... What exactly did the hero want to say?
British comedies... yeah... I like them. Of course, I always make some effort to understand them... Sometimes it's necessary to consult one or two dictionaries to find all meanings of a word (direct or figurative)... But this is not a problem.

Having said all that, do you care about mistakes? Especially when even natives err now and then
I will always care about my mistakes. I can't do anything with this.

Thanks for answer and for usefull links!

u r wlcm

I will always care about my mistakes. I can't do anything with this.

as a rule, much reading helps to settle the issue

have a nice summer weekend