Can / can't, must / mustn't, countable and uncountable

http://www.englishexercises.org/makeagame/viewgame.asp?id=3341
http://www.saberingles.com.ar/curso/lesson13/05.html
http://www.saberingles.com.ar/curso/lesson13/08.html
http://www.saberingles.com.ar/curso/lesson13/07.html
http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-18629.php
http://roble.pntic.mec.es/jheb0015/Ework/Must_1.htm
http://www.englishexercises.org/makeagame/viewgame.asp?id=2786
http://www.englishexercises.org/makeagame/viewgame.asp?id=7521
http://s.mound.free.fr/skyblues67/modals/mustn%27t.htm

countable and uncountable
http://www.eslgamesplus.com/countable-uncountable-a-an-rally/
http://www.engames.eu/countable-and-uncountable-nouns/
https://elt.oup.com/student/horizonscee/games/frog2?cc=ar&selLanguage=en
http://www.anglomaniacy.pl/grammar-nouns-testyourself3.htm
http://www.englishexercises.org/makeagame/viewgame.asp?id=3246
http://www.myenglishpages.com/site_php_files/grammar-exercise-countable-uncountable-nouns.php
http://a4esl.org/q/j/ck/ch-countnouns.html