Hi Camilo 'A' and 'an' are indefinite articles in English, they are used to refer to an unspecified thing, quantity or group. There is a general rule you can memorize so you'd know in the future when to use 'a' or 'an': 'a' is used when it precedes a word beginning with a consonant whilst 'an' is used when it precedes a word beginning with a vowel. E.g.: 'a' sheep, 'a' dog', 'a' flower / 'an' idea', 'an' operation', 'an' apple. To answer your question, these indefinite articles are used when you're using a noun in your sentence. E.g.: 'a' beautiful girl - you have to use 'a' because you're referring to the noun 'girl' (the adjective 'beautiful' is followed by the noun 'girl') she is beautiful - you don't use an article because the adjective 'beautiful' is not followed by a noun 'a' great idea - you use 'a' because the adjective 'great' is followed by the noun 'idea' your idea is great - you don't use an article because the adjective 'great' is not followed by a noun I hope this helps! Regards Karen

He is a speaker and writer He is an architect and a dancer When the two things are related, it is possible to leave out the second "a" in the sentence. When they are a new idea, it is not. So for your example, it should read: he is an old, tall Brazilian and a student Because the student is a new idea However, in the following example: He is a proud, hardworking Brazilian father and student here student is not a new idea, and so it is more like a list where you do not have to repeat the a He took a kettle, bottle of milk and jar of coffee into the sitting room. This is a list and "a" doesn't need to be repeated He took a kettle and an orange into the living room and then took a book and a cat back into the kitchen - where they are not logically related and it makes more sense to put a/an

Thank you for answer my question.

She is a student. She is a (adjectives) student. She (a student) is adjectives. The adjectives don't need an article "a". She is beautiful. She has red hair and blue eyes. She has a hat. ("hat" noun, needs an article)

"an" when next word starts with a vowel sound, not necessarily just a vowel.