> (by the way, i'm sorry for my english skills)
If you feel the need to append this statement, that's a good sign that you don't need to. Your English is fine (should be "schools teach", not "schools teaches", and I wouldn't have used "sample for" there, but who cares -- it's clear and unambiguous). It's the morons who don't care that end up being painful to read.
If you feel the need to append this statement, that's a good sign your comment will detract from the discussion.
It's more useful to invite constructive feedback than to apologize preemptively; that's what I'd recommend people do. Add onto this that, culturally, Americans tend to appreciate such invitations more than they appreciate apologies. (I can't speak to other cultures; I'm about 99% certain there are some major world-spanning ones where this is not true.)
The latter is usually needless, and can even imply that not knowing English well enough should be a source of shame, which is why it often draws calls saying not to apologize. It'd be like a 2m tall person apologizing for not being tall enough – you're already taller than most people, there's nothing to apologize for. ;)
I have noticed that people tend to jump on others language skills in an indirect attack on the person when its the idea they disagree with. For some it is easier to dismiss an idea they do not agree with by attacking the person than refuting the argument.
Working with many foreigners I have run into the apology style more than once, they have good standing and do not wish to be dismissed for merely bad language skills. I live here and my use of the language is atrocious.
Anyhow, can anyone recommend a book or some articles on how to improve writing skills, especially of technical nature ?
Also, I apologize profusely for some of our ridiculous grammatical rules. I'm a native speaker, so I don't think much of it, but I'm amazed at how poor some of the "rules" are.