Théorie :

https://la-conjugaison.nouvelobs.com/fle/exprimer-la-cause-76.php

Exercices :

https://www.francaisfacile.com/exercices/exercice-francais-2/exercice-francais-17457.php

https://www.francaisfacile.com/exercices/exercice-francais-2/exercice-francais-49146.php

http://www.didieraccord.com/exercices/index.php?ex=2.3.1.5

https://www.podcastfrancaisfacile.com/cours/expression-de-la-cause.html

http://www.lefrancaispourtous.com/ex_cause1.htm