The normal structure of sentences in Portuguese does not require an auxiliary, no matter the verb tense or what kind of sentence we are talking about.
Basically, the structure of a sentence is SUBJECT+VERB+COMPLEMENT, and the complement can be a combo of article+noun+adjective and many others, or just one of them.
The main sentence form we know are below. In the table, you will be able to visualize the difference in the structure between English and Portuguese.
INTERROGATIVE SENTENCES:
Different from English, what matters here is the intonation used when speaking. That will define if you are questioning, affirming or denying your statement. See as follows:
VOCAS
QUER
UMA
COCA-COLA
?
Subject
Verb
Article
Noun
DO
YOU
WANT
A
COKE?
Auxiliar
Subject
Verb
Article
noun
AFFIRMATIVE SENTENCES:
In this case, the sentence has the same structure. There is no other sentence term apart from the subject, verb and complement. To emphasize the action, we just use the intonation when speaking the verb. Again, there is no auxiliary to use in such case as in English.
Eles
comem
comida
chinesa.
Subject
Verb
Noun
Adjective
They
eat
Chinese
food.
Quero
ver
o
pA?r-do-sol.
Main Verb
Second verb
Article
Noun
Hidden Subject
I
Want
to see
the
sunset.
NEGATIVE SENTENCES:
For this kind of sentence, we follow the same pattern as the above ones. No auxiliary is used together with NO. We just place the word NA?O in front of the verb, no matter if it is to be or any other verb.
Eles
NA?O
comem
comida
chinesa.
Subject
NO without auxiliary
Verb
Noun
Adjective
NA?O
quero
ver
o
pA?r-do-sol.
NO, hidden subject
Main Verb
Second verb
Article
Noun
They
DON’T
eat
Chinese
food.
I
DON’T
want
to see
the sunset.
Subject
AUXILIARY
Verb
complement
*It doesn’t matter if the sentence has no shown subject, the NA?O particle still comes before the verb, even in the beginning of the sentences.
