As there is no "h" after the "c" in cat (no lention) it is hers rather than his Mo+"h" = my Do+"h" = your A+"h" = his A = her Ár+urú(eclipsis) = our Bhur+urú = your (plural) A+urú = their
For consonants ONLY
For Vowels; (same order of person)
A+"h" (at start of word eg. a húll- her apple)
Ár+"n" (at start of word eg. a núll- their apple)
In a situation where the subject doesn't undergo lenition/eclipsis - e.g. "Is maith lena rón uisce," - how does one determine whether it is his, her or their seal that likes water? Or does the sentence structure have to change to make it explicitily clear? Sorry if this is a silly question with an obvious answer.
lena is a compound of the preposition le and the possessive adjective a.
a is in the table in the Tips for the Possessive skill (https://www.duolingo.com/skill/ga/Possessives/tips-and-notes)
a is NOT a pronoun, so lena is NOT a prepositional pronoun, and so lena is not in the table of prepositional pronouns in the Prepositions 1 skill (https://www.duolingo.com/skill/ga/Prepositions-1/tips-and-notes).