If I'm explaining a specific rule to someone. I would like to say that the rule has exceptions. How to choose the correct proposition?
- This rule is not valid in all cases.
- This rule is not valid for all cases.
Are these sentences commonly used among native speakers? or Is there more powerful sentence?
Edit: I'm teaching Arabic to someone. I need to tell him if he sees a specific character at the end of a word. This word is categorized under "feminine words". But it is not a general rule. It has some exceptions. There are some irregular words.