el artículo a/an:
https://www.englishexercises.org/makeagame/viewgame.asp?id=1203
https://speakspeak.com/english-grammar-exercises/elementary/using-a-and-an-correctly-indefinite-articles
plurales:
https://www.englishexercises.org/makeagame/viewgame.asp?id=303
vocabulary:
https://www.englishexercises.org/makeagame/viewgame.asp?id=4023
repaso del verbo to be:
https://www.esl-lounge.com/student/grammar/1g7-to-be-gap-fill.php
https://www.esl-lounge.com/student/grammar/1g8-to-be-positive-or-negative-gap-fill.php