Was were

http://www.ingenierogeek.com/2013/11/curso-ingles-medio-pasado-verbo-to-be-oraciones-ejemplos-was-were.html

https://www.englisch-hilfen.de/en/exercises/tenses/was_were.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=5211

https://agendaweb.org/verbs/to-be-past-exercises.html