Invariabilidade do particípio

In Portuguese, compound tenses are formed by combining a helper verb with a main verb. The helper (or auxiliary) verb is almost always ter (to have) or occasionally haver (to have/there is). The main verb takes the form of the past participle. Usually, participles end in -ado or -ido. The magic happens here: when ter or haver is the helper, the participle is "invariable." This means it is locked. It is stuck in the masculine singular form. You might be talking about your sisters, your house, or your problems. The participle doesn't care. It keeps that -o at the end. It functions as a single unit with the auxiliary verb. They are like a specialized team. The auxiliary verb handles the person, the number, and the time. The participle just provides the core meaning of the action. It's like a passenger in a car; the driver (ter) does all the work of turning and shifting, while the passenger (the participle) just sits there looking the same the whole trip.

1. 1Creating these sentences is a simple five-step process.
2. 2Identify your subject (who is doing the action?).
3. 3Choose your auxiliary verb (99% of the time, this will be ter).
4. 4Conjugate ter to match your subject and the tense you need.
5. 5Take your main verb and turn it into its past participle form.
6. 6Ensure that participle ends in -o (masculine singular).
7. 7Let's look at the verb estudar (to study).
8. 8For "I": Eu tenho estudado.
9. 9For "She": Ela tinha estudado.
10. 10For "They (women)": Elas terão estudado.
11. 11Notice how estudado never changes? It doesn't become estudada or estudados. It is rock solid. Even if you are talking about a group of women who have studied for a job interview, they will say: Nós temos estudado muito para a entrevista.

You use this invariable form in all "Active" compound tenses. This includes the Pretérito Perfeito Composto (I have been doing), the Pretérito Mais-que-perfeito Composto (I had done), and the Futuro do Presente Composto (I will have done).

• Imagine you are at a restaurant. You want to tell the waiter you have already ordered. You say: Nós já tínhamos pedido.
• Imagine you are in a job interview. You want to say you have worked in many cities. You say: Eu tenho trabalhado em várias cidades.
• Imagine you are talking about your female friends. You want to say they have arrived. You say: Elas tinham chegado.

In every real-world scenario where you use "have/had + [verb]", the rule applies. It is the standard for expressing completed actions or ongoing states in the past, present, or future.

This is the most important part to remember: this rule only applies when the auxiliary is ter or haver. If you switch to the verbs ser (to be) or estar (to be), the rule breaks. This happens in the Passive Voice or when the participle acts as an adjective.

• Passive Voice: A carta foi escrita (The letter was written). Here, escrita matches carta because the auxiliary is ser.
• Compound Tense: Eu tinha escrito a carta (I had written the letter). Here, escrito is invariable because the auxiliary is ter.

Think of it like a traffic light. Ter and Haver are green lights for the -o ending. Ser and Estar are red lights that force you to stop and change the ending to match the noun. If you are describing a state (The door is closed), you use agreement: A porta está fechada. If you are describing an action you performed (I have closed the door), you use the invariable form: Eu tenho fechado a porta.

The most frequent mistake is "Over-Agreement." Because Portuguese usually loves agreement, your brain will scream at you to change the ending. You will see Elas (They, feminine) and want to say Elas tinham compradas as roupas. This is wrong. It must be comprado.

Another mistake is confusing the passive voice with compound tenses. A student might say Nós tínhamos convidados when they mean Nós tínhamos convidado (We had invited). Convidados with an 's' would actually mean "guests" (a noun), which changes the whole meaning of your sentence!

Finally, watch out for irregular participles. Even irregulars like feito (done) or visto (seen) remain invariable. You would never say Elas tinham feitas; it is always Elas tinham feito.

Let's compare the Active Compound Tense with the Passive Voice side-by-side to see the difference clearly.

Active: A Maria tinha aberto as janelas (Maria had opened the windows).

Passive: As janelas foram abertas pela Maria (The windows were opened by Maria).

In the active sentence, the focus is on Maria's action. We use tinha (from ter), so aberto is frozen. In the passive sentence, the focus is on the windows. We use foram (from ser), so abertas must match the windows.

Also, contrast it with the participle as an adjective:

Adjective: As janelas estão abertas (The windows are open).

Compound Tense: Nós temos aberto as janelas todos os dias (We have been opening the windows every day).

One describes a condition (open), the other describes a repeated action (have been opening).