http://www.focus.olsztyn.pl/en-exercises-conditionals.html
https://www.ego4u.com/en/cram-up/tests/conditional-sentences-4
https://www.myenglishpages.com/site_php_files/grammar-exercise-conditionals.php
https://first-english.org/english_learning/if_clauses_conditional/66_if_clauses_conditional_exercises_test.htm
http://www.englishlessonsbrighton.co.uk/the-conditionals-rules-and-exercises/
https://www.liveworksheets.com/search.asp?content=conditionals&language=&subject=&level=&age=&Search=Search
https://www.englisch-hilfen.de/en/exercises_list/if.htm
https://www.english-4u.de/grammar_exercises.htm
https://www.english-grammar.at/online_exercises/if-clauses/if-clauses-index.htm
https://www.e-grammar.org/if-clauses/
https://www.liveworksheets.com/search.asp?content=conditionals