For practicing:
https://agendaweb.org/grammar/articles-definite-the-exercises.html;
https://www.englisch-hilfen.de/en/exercises/nouns_articles/article_the.htm;
https://www.englishexercises.org/makeagame/viewgame.asp?id=71;
https://www.curso-ingles.com/en/practice/exercises/the-definite-article;
https://elt.oup.com/student/project/level3/unit04/grammar/exercise2?cc=lt&selLanguage=en;