Form 6b. Countable and uncountable nouns

http://www.englisch-hilfen.de/en/exercises/nouns_articles/countables.htm;
http://www.perfect-english-grammar.com/nouns-countable-and-uncountable-exercise-1.html;
http://a4esl.org/q/j/km/mc-noncount.html;
http://www.carmenlu.com/first/grammar/countable1_1.htm;
http://www.better-english.com/easier/counta.htm;
http://learnenglish.britishcouncil.org/ar/english-grammar/nouns/count-nouns.