EXERCISES: PLURAL OF NOUNS

http://www.grammar-quizzes.com/agree1a.html

http://www.grammar-quizzes.com/agree1b.html

http://www.myenglishpages.com/site_php_files/grammar-exercise-plural.php

http://www.agendaweb.org/grammar/plural-exercises.html

http://www.englishexercises.org/makeagame/viewgame.asp?id=723

http://www.englisch-hilfen.de/en/exercises_list/substantiv.htm

https://www.ego4u.com/en/cram-up/grammar/nouns/exercises?03