Learn Hardcore Portuguese (Portugal): É importante cumprir cada regra do exame. - It is important to follow each rule of the exam.

In Portuguese, you can use an impersonal construction with é + adjective + infinitive to talk in a general way, without mentioning who is doing the action.

É importante cumprir cada regra do exame.
Literally: Is important to follow each rule of the exam.

The understood subject is something like “people in general” or “anyone taking the exam”, but it’s not said explicitly. This is very common in Portuguese when giving advice, rules, or general statements:

É difícil aprender chinês. – It’s difficult to learn Chinese.
É proibido fumar aqui. – It’s forbidden to smoke here.

So there is no subject simply because the sentence is impersonal and general, just like English “It’s important to follow…”, where “it” is also just a dummy subject, not a real thing.

Why is cumprir in the infinitive instead of a conjugated verb like cumprimos or cumpro?

After this impersonal pattern é + adjective, Portuguese normally uses the infinitive to express the action:

É importante cumprir… – It is important to follow…
É necessário estudar. – It is necessary to study.
É proibido estacionar. – It is forbidden to park.

If you conjugated the verb, the structure would change and would no longer be this simple impersonal pattern. You would need to introduce a subject and usually que + subjunctive:

É importante que nós cumpramos cada regra do exame.
– It’s important that we follow each rule of the exam.

So with é importante + infinitive, you stay in the impersonal, general form. The infinitive is the natural choice here.

Could you say “É importante de cumprir cada regra do exame”?

No, that would be incorrect in standard Portuguese.

With this structure é + adjective + infinitive, you do not use de:

✅ É importante cumprir cada regra do exame.
❌ É importante de cumprir cada regra do exame.

There are other structures where you do see de + infinitive, but they are different grammatically:

Tenho de estudar. – I have to study.
Antes de sair, fecha a porta. – Before leaving, close the door.

With é importante / é necessário / é bom / é proibido, you go directly to the infinitive, no de.

What’s the difference between cumprir and verbs like seguir or obedecer in this sentence?

All can relate to rules, but they’re used slightly differently:

cumprir regras – to comply with / fulfil the rules
This is a very standard collocation with regras:
- cumprir as regras de trânsito – obey traffic rules
seguir regras – to follow rules (more literal “follow the steps”)
Sounds fine, but a bit more like following procedures.
obedecer às regras – to obey the rules
Here regras takes a preposition: obedecer a algo.

In your sentence, cumprir is the most natural and idiomatic choice:

É importante cumprir cada regra do exame.

You could say:

É importante obedecer às regras do exame.

but cumprir regras is the default collocation.

Why is it cada regra (singular) and not cada regras (plural)?

In Portuguese, just like in English, cada (each) is followed by a singular noun:

cada regra – each rule
cada aluno – each student
cada dia – each day

So:

✅ cada regra do exame – each rule of the exam
❌ cada regras do exame

Even though you mean all rules taken one by one, grammatically you always keep the noun in the singular after cada.

What’s the difference between cada regra do exame and todas as regras do exame?

Both can be translated as “all the exam rules”, but the nuance is a bit different:

cada regra do exame – each rule of the exam
Emphasises the individual rules one by one. It suggests you shouldn’t neglect any single rule.
todas as regras do exame – all the rules of the exam
Emphasises the whole set of rules as a group.

Compare:

É importante cumprir cada regra do exame.
– You must respect every single rule, without exception.
É importante cumprir todas as regras do exame.
– You must respect all the rules (focuses more on the totality).

Both are correct. The original version adds a little extra stress on each individual rule.

What does do in do exame mean exactly?

do is a contraction of the preposition de + the masculine singular article o:

de + o = do

So:

cada regra do exame
= cada regra de o exame (which is not used as-is)
= each rule of the exam

This contraction is mandatory in normal speech and writing. You virtually never say de o exame; you always say do exame.

Why is it do exame and not no exame or para o exame?

The preposition de here expresses possession/belonging or association, like English “of”:

as regras do exame – the rules of the exam / the exam’s rules

Other prepositions would change the meaning:

no exame = em + o exame – in the exam
- as regras no exame – the rules in the exam (sounds like rules that are inside the test paper)
para o exame – for the exam
- as regras para o exame – the rules for the exam (rules that apply to or are meant for the exam)

The most natural way to say “the exam rules” is as regras do exame with de → do.

Can I invert the order and say Cumprir cada regra do exame é importante?

Yes, that is perfectly correct:

É importante cumprir cada regra do exame.
Cumprir cada regra do exame é importante.

Both are grammatical and mean the same thing.

The difference is mostly about emphasis and style:

Starting with É importante… is very common for general statements and rules.
Starting with Cumprir cada regra do exame… puts more focus on the action (complying with each rule).

In everyday speech and writing, the original version (É importante cumprir…) is more frequent for this type of sentence.

How would I say this if I want to talk specifically about “you” (singular), rather than people in general?

There are a few natural ways, especially in European Portuguese:

Using the personal infinitive (very common in European Portuguese):
- É importante cumprires cada regra do exame.
  – It’s important that you follow each rule of the exam.
Here cumprires is the 2nd person singular personal infinitive, explicitly referring to tu (you, informal singular).
Using the subjunctive with que:
- É importante que cumpras cada regra do exame.
  – It’s important that you follow each rule of the exam.

Both are correct. In European Portuguese, the personal infinitive (cumprires) sounds very natural and is common in speech. In Brazilian Portuguese, the version with que + subjunctive (que você cumpra) is more typical:

É importante que você cumpra cada regra do exame.

Is there a more formal or stronger way to express this idea?

Yes, you can make it sound more formal or more forceful in several ways:

É obrigatório cumprir cada regra do exame.
– It is mandatory to follow each rule of the exam.
É indispensável cumprir cada regra do exame.
– It is indispensable/essential to follow each rule of the exam.
Deves cumprir cada regra do exame.
– You must follow each rule of the exam. (using dever)
Tens de cumprir cada regra do exame. (informal)
– You have to follow each rule of the exam.

The original É importante… is strong but still a bit softer than é obrigatório / deves / tens de, which sound more like strict commands.

How is cumprir pronounced in European Portuguese?

In European Portuguese, cumprir is roughly:

/kũˈpɾiɾ/

Key points:

cu- → [kũ]: nasal u, similar to saying “koon” but shorter and with nasalization.
-mpr- → [mpɾ]: the m mainly nasalises the vowel; the p and r are both pronounced.
-rir → [ɾiɾ]: ri as in “ree”, and final r is usually a soft tap or almost silent depending on region and speed.

Very approximately to an English ear: “koon-PREER” (with nasal oo and a light tap on the first r).

Is there any difference between European Portuguese and Brazilian Portuguese in this sentence?

Grammatically, the sentence É importante cumprir cada regra do exame. is fine in both European Portuguese (PT-PT) and Brazilian Portuguese (PT-BR).

Some tendencies:

Vocabulary:
- In Brazil, prova is very common for a test/exam:
  - É importante cumprir cada regra da prova.
- In Portugal, exame is very natural here, though prova is also used in some contexts.
Pronunciation is quite different between PT-PT and PT-BR, but the structure is the same.
Both varieties accept é importante + infinitive.
If you specify you:
- PT-PT: É importante cumprires cada regra do exame.
- PT-BR: É importante que você cumpra cada regra do exame.

But your original sentence, as given, works in both varieties.