Respuesta :
A: before a singular word starting with a consonant that is firstly talked about
An: before a singular word starting with a vowel that is firstly talked about
The: before a singular/plural word that has been talked about
An: before a singular word starting with a vowel that is firstly talked about
The: before a singular/plural word that has been talked about
The is used to refer to specific or particular nouns, and is definite
A/an is used to change non-specific or non-particular nouns and are indefinite