Dia daoibh 'chuile dhuine.

Táim ag cleachtadh an copula aríst agus níl a fhios a'm cén fáth go bhfuil na abairtí seo difriúil;


deir sé gurb í cait mo chomharsa bhéal dorais agus Deir sí gur as Conamara í. .

It's the "gur" part that is throwing me. I thought "gur" changes to "gurb" before a vowel. So why is it "gur" and not "gurb" in the second sentence?

'maith agaibh

gurb before pronouns, adjectives, amhlaidh (gurb é, gurb í, gurb ea, gurb iad, gurb álainn, gurb amhlaidh, ...)
gur before nouns, prepositions, prepositional pronouns, adverbs (gur amadán, gur as, gur inti, gur anois, ...)

gur is a bit different from other forms in -r. It is arb, sularb, darb before vowel in all words.

go raibh maith agat a Labhráis Was racking my brains over it.