The subtitle of this lengthy but packed article was: "Can a native speaker of English make mistakes?" A provocative question, which leads the article to explore prescriptivism, descriptivism, and a history of language change, as well as some resources for 'correct English'. For A2s, and budding A2s alike.
Sane English
http://greatsfandf.com/english-language.php
Sane English
http://greatsfandf.com/english-language.php