https://www.englisch-hilfen.de/en/exercises_list/if.htm
https://www.ego4u.com/en/cram-up/grammar/conditional-sentences
https://www.perfect-english-grammar.com/conditional-exercises.html
https://www.englishexercises.org/buscador/buscar.asp?nivel=any&age=0&contents=conditional
https://www.myenglishpages.com/site_php_files/grammar-exercise-conditionals.php
Refuerzo de teoría: https://inglescarmelitaslb.files.wordpress.com/2011/05/conditional-sentences.pdf