English

I learnt proper English some years ago. Strict, in the grammar sense, English. However, more and more, I see my abilities being deteriorated due to the internet. Even native speakers make constant mistakes, being some horrendous, which from those, unfortunately, I am beginning to be a victim, as I can notice them in my own speaking.

Would someone mid recommending a good book I can download from which I can revise some concepts?
Also, is there any online resource for prepositions (these I always had trouble with)?

Thank you, /lang/

You come off more like someone who wants to appear superior to others rather than someone genuinely interested in communicating ideas. You're better off just reading literature and seeing firsthand what's considered to be great writing.

If it's conversation you're worried about, I think you're taking this way too far. Learning a language and speaking a language are not about "dominating the grammar". They're about talking to other people.