"Vegetables are in the dinner."
Translation:Tá glasraí sa dinnéar.
Nouns beginning with D, S, or T aren’t lenited after sa (and after many other prepositions + an).
What happens to "the" here? Is there a difference between "in a" or "in the" in Irish sentence construction?
You use san before a word that starts with a vowel - san uisce.
Because sa lenites, words that start with f+vowel also use san, as fh is silent, exposing the vowel - san fhorais.