[Laurent55]

I totally agree with you when you speak against "building common but erroneous grammatical structures into a coursebook as a productive model", which is what more and more coursebooks do! To put us in touch with real English, they say, but more probably, because real English comes in so many different guises that it enables them to expand learning material for ever, and so their sales! Compactness is no longer the order of the day. Pity!