Δραστηριότητες εμπέδωσης:
https://agendaweb.org/exercises/grammar/articles-a-an
https://agendaweb.org/exercises/grammar/a-an-multiple
http://static.digischool.nl/en/grammar/hotpot/lidwoorden/aofan2.htm
https://www.esl-lounge.com/student/grammar/2g45-indefinite-article.php