Ah, the blessed crasis, who has never had problems or doubts when using the crasis, right? We have several types of contraction or combination in the Portuguese language. This contraction occurs due to a preposition with another word.
Observe this example:
*Where (preposition a + adverb where)
*Ao (preposition a + article o)
in contraction, words lose some letter at the time of joining. Watch:
*da (preposition de + article a)
*na (preposition in + article a)
but there is a case of contraction that leaves some room for doubt. See the example:
Crasis. Junction of the preposition ''a'' with the definite article ''a(s)'', or even the preposition ''a'' with the initials of the demonstrative pronouns that(s), that(s), that or with pronoun relative to which (which). Graphically, the fusion of the vowels ''a'' is represented by a grave accent, marked in the opposite direction to the acute accent: à.
But how do you know and whether or not you should use the crasis? A question that doesn't want to be silenced. A tip is to replace the crasis with ''ao'' and the feminine noun with a masculine noun, if this preposition is accepted without compromising its meaning, then it is definitely already a crasis.
Let's look at some more examples: I went to the pharmacy, replacing ''à'' with ''ao'' would be I went to the supermarket. Therefore, the use of the crasis is correct.
I watched the play that is on display, replacing ''à'' with ''ao'' would be I watched the Brazilian team's volleyball game.
Important to say: The crasis does not occur: before masculine words; before verbs, personal pronouns, city names that do not use the feminine article, the word casa when it has the meaning of home itself, the word land when it has the meaning of soil and expressions with repeated words (day to day).
