Present Subjunctive of Regular -ir

The subjunctive is a mood, not just a tense. It usually needs two parts to work. First, you have a main clause with a "trigger." Second, you have the subjunctive clause. These two parts are almost always joined by que. You also need a change of subject. For example: "I want that you open the door." I am the first subject. You are the second subject. If I want to open the door myself, I use the infinitive. But if I want *you* to do it, the subjunctive steps in. It is like a relay race. I pass the action to you through the word que.

1. 1Forming regular -ir verbs is actually quite logical. You just need to remember the "Opposite Day" rule. Follow these three simple steps:
2. 2Start with the eu form of the present indicative. For abrir, this is abro.
3. 3Drop the -o ending. Now you have the stem: abr-.
4. 4Add the "opposite" endings. Since it is an -ir verb, you use -a endings.
5. 5Here is the full conjugation for partir (to leave):
6. 6Eu parta
7. 7Tu partas
8. 8Ele/Ela/Você parta
9. 9Nós partamos
10. 10Vós partais
11. 11Eles/Elas/Vocês partam
12. 12Notice how the -i from the infinitive disappears. It is replaced by the letter a. Think of it as a grammar swap. It feels strange at first, but your brain will adapt quickly. Yes, even native speakers sometimes have to pause for a microsecond!

You use the subjunctive in specific "WEIRDO" scenarios.

• Wishes: When you want someone to do something. Quero que você abra o presente. (I want you to open the gift.)
• Emotions: Expressing how you feel about an action. Sinto muito que eles partam amanhã. (I'm sorry they are leaving tomorrow.)
• Impersonal Expressions: General statements of opinion. É importante que nós decidamos logo. (It is important that we decide soon.)
• Requests: Asking or telling someone to act. Peço que você não desista. (I ask that you don't give up.)
• Doubts: When you aren't sure about something. Duvido que ela admita o erro. (I doubt she will admit the mistake.)

Imagine you are in a job interview. You might say: Espero que a empresa me contrate. (I hope the company hires me.) Or at a restaurant: Sugiro que você divida a sobremesa. (I suggest that you share the dessert.) It adds politeness and nuance to your speech.

Do not use the subjunctive for facts. If something is 100% true or certain, stay with the indicative.

• Certainty: Eu sei que ele parte hoje. (I know he leaves today.) No doubt here!
• No Subject Change: Eu quero partir. (I want to leave.) Since I am the one leaving, use the infinitive.
• Observations: Vejo que você abre a janela. (I see that you are opening the window.) This is a physical fact happening now.

Think of it like a grammar traffic light. Green light (Indicative) is for facts. Yellow light (Subjunctive) is for the "maybe" zone. If you are sure, don't flip the vowel!

The biggest mistake is using the wrong vowel. Because it is an -ir verb, many people want to use -e. They say que ele parte instead of que ele parta. Remember: -ar verbs take -e, and -ir/-er verbs take -a. It is a total switch!

Another mistake is forgetting the que. Without que, the sentence usually falls apart. Also, watch out for the nós form. It is partamos, not partimos. If you say partimos, you are talking about the past or the present fact. Using the wrong vowel can change your meaning entirely. It is like wearing socks on your hands—people will understand you, but it looks a bit funny.

How does this differ from the Present Indicative?

• Indicative: Você abre. (You open - a fact).
• Subjunctive: ...que você abra. (...that you open - a wish or possibility).

How does it differ from -ar verbs?

• Falar (-ar): que eu fale (uses -e).
• Abrir (-ir): que eu abra (uses -a).

It is a mirror image. If the verb ends in -ar, the subjunctive ends in -e. If the verb ends in -er or -ir, the subjunctive ends in -a. Once you see this symmetry, you can't unsee it!