In its modern form, English has been stripped of some grammatical features still very much in use in romance languages like Portuguese.
In English, only reminiscences of the subjunctive verb mood remain in conditional phrases such as
“I’d be careful if I were you”
“Eu tomava/tomaria cuidado se eu fosse você,”
and in fixed expressions such as
“If he decides to leave me, well so be it”
“Se ele decidir deixar-me, pois bem então que seja assim,”
whereas in Portuguese you do not make use of elaborate language without using the subjunctive.
In the case of the imperfect aspect of the past verb tense, two compound forms fortunately remain in use in English covering the aspects of reoccurrence, used to plus infinitive –
“I used to work when I was a teenager”
“Eu trabalhava quando era adolescente”,”
and continuity, was/were plus gerund –
“I was singing when she knocked the door”
“Eu cantava/ estava cantando quando ela bateu à porta,”
whereas in Portuguese the imperfect is also used to show background contrast between two past facts, states or actions:
“Eu tinha 15 anos quando os meus pais se divociaram”
“I was 15 when my parents divorced”
“Fazia frio então decidimos entrar na Catedral”
“It was cold so we decided to go into the Cathedral.”
In Portuguese, the stem of the regular verbs receives a special ending to form the imperfect as in Latin.
Articles, however, did not exist in Latin, and their gradual introduction into modern languages did not follow any consistent pattern of rules. Hence in English, the definite article is not marked for its plural or feminine forms,
“the boy/ the boys”
“the girl/ the girls”
“o menino/ a menina”
“os meninos/ as meninas,”
whereas in Portuguese, determiners are almost without exception marked by their plural and feminine forms in noun phrases to show concord. Unaware of this, an Englishman may refer to his Brazilian girlfriend as his Brazilian boyfriend:
“o meu namorado brasileiro”
“my Brazilian boyfriend”
“os meus namorados basileiros”
“my Brazilian boyfriends”
“a minha namorada brasileira”
“my Brazilian girlfriend”
“as minhas namoradas brasileiras”
“my Brazilian girlfriends.”
The verb to be in English can be translated into at least four different forms in Portuguese:
“Where’s the rail station?”
“Onde é que fica a estação de trem/comboios? (verb ficar for geographical localization),”
“Are you English, sir?”
“O senhor é inglês? (verb ser for definite statements),”
“Are you hungry?”
“Está com fome? (verb estar for temporary states),”
“How are things?
“Como é que andam as coisas? (verb andar for progressive states).”
There are two imperative forms of the verb in English with their respective negative forms: a general form
“Stop it! Don’t stop it!”
and when the speaker is included
“Let’s open the window! Let’s not open the window!”
In Portuguese, there are five forms of the imperative with their respective negative forms: an informal
“Para! Não pares!”,
a formal
“Pare! Não pare!”,
when the speaker is included
“Paremos! Não paremos!” (formal) or
“Vamos parar! Não vamos parar!” (informal)
“Let's stop it! Let's not stop it!”
and a you plural form
“Parem! Não parem!
Given all this, I presume that for an English native speaker learning Portuguese, it might feel like going from an unsophisticated language into a sophisticated one.