PASSIVE VOICE- THEORY

Some useful pages with theory about the passive voice in English:


http://www.myteacherpages.com/webpages/alfonsolopez/files/Passive%20Voice.pdf

https://learnenglish.britishcouncil.org/es/english-grammar/verbs/active-and-passive-voice

http://www.ef.com.es/recursos-aprender-ingles/gramatica-inglesa/voz-pasiva/ ((In Spanish)

http://www.ef.com.es/recursos-aprender-ingles/gramatica-inglesa/modos-alternativos-formar-voz-pasiva/