"Yes, I have a sore arm."
Translation:Oes, mae braich dost gen i.
Gan/gyda if it is attached or localised (mae bysedd tost ganddo fe; pen tost 'da fi, clust dost gyda Ceri; mae gen i gur pen; ...)
Ar... if it is more of a generalised infection sort of thing (mae annwyd arno fe; mae'r ffliw arna i; mae'r dannoedd ar Dewi; ...)
cael is not used for ownership or for 'having' anything in the sense of a bad arm or leg, etc. See my earlier answer above and the course notes for this section.
Oes as 'Yes' is used along with mae..., in the sense of something is existing:
- Oes teigr yn yr ardd? Oes, mae e ar ben y cwt. - Is there a tiger in the garden? Yes, it's on top of the shed.
- Oes braich dost gen/gyda ti? *Oes. - Have you got a sore arm? *Yes.