can-can´t exercises

http://mbonillo.xavierre.com/exercises/eso1/1eso2007/can3.htm
http://www.ecenglish.com/learnenglish/lessons/can-or-cant
http://www.englisch-hilfen.de/en/exercises/modals/can3.htm
http://www.1-language.com/englishcourse/unit18_grammar_exs2.htm