Why is this plural?
I was recently strengthening a lesson in Prepositions 3 (I believe) and one of the sentences was "C'est au-dessus de mes forces". The translation was "It is beyond my strength". I typed "C'est au-dessus de ma force" and was counted wrong because "la force" is "the strength" singular. I'm not sure why the singular is incorrect and the plural is correct. Is this a bug? If it's not, then why was my answer wrong? Can any native French speaker help?
I'm not a native French speaker, but I'm a native Spanish speaker and I have found that the two languages have a lot in common especially in usage. It's common in Spanish, and apparently also in French, to use "mes forces" ("mis fuerzas" in Spanish) in this type of sentence. The translation to Spanish matches perfectly although the translation to English is different. I don't think it's a rule per se, but just a usage issue.