Brazilian Portuguese Grammar

The Portuguese preposition a accompanies a large number of prepositional verbs and introduces the prepositional object of nouns, adjectives and adverbs:

Não fui a Paris no ano passado. => I didn't go to Paris last year. (prepositional verb)

Sugestão aos leitores => Suggestion to the readers. (noun followed by preposition)

Ele está disposto a cooperar. => He's willing to cooperate. (adjective followed by preposition)

Preposition a can also appear in combinations and contractions with definite articles:

Preposition a	Definite articles	Combinations and contractions	Example	English
a	o	ao	Fui ao cinema.	I've been to the movie theater.
a	os	aos	Fui aos rodeios.	I've been to the rodeos.
a	a	à	Fui à festa.	I've been to the party.
a	as	às	Fui às lojas.	I've been to the stores.

Preposition a can precede relative pronouns and interrogative pronouns , e.g.:

a que	preposition a + relative pronoun que	Vi o teatro a que você se referiu ontem.	I saw the theater that you referred to yesterday.
à qual	preposition a + relative pronoun a qual	Vi a casa à qual você se referiu ontem.	I saw the house that you referred to yesterday.
A quem	preposition a + interrogative pronoun quem	A quem pertence esse livro?	Who does that book belong to?
Aonde	preposition a + interrogative pronoun onde	Aonde você vai?	Where are you going (to)?

a	Qual pessoa você acha mais interessante, a de preto ou a de vermelho?	Which person do you find more interesting, the one in black or the one in red?
as	Quais pessoas você acha mais interessantes, as de preto ou as de vermelho?	Which people do you find more interesting, the ones (those) in black or the ones (those) in red?