Learn Hardcore Portuguese (Brazil): Se você ainda tiver alguma dúvida, pode perguntar depois da aula. - If you still have any doubt, you can ask after class.

Tiver is the future subjunctive form of ter. In Portuguese, when you talk about a possible future situation introduced by se (if), you normally use the future subjunctive, not the present tense.

Se você ainda tiver alguma dúvida…
= If you still have any questions (at that future moment)…

Compare:

Se você tiver tempo, me liga.
If you have time, call me. (in the future)
Se você tem tempo, por que não me ajuda?
If you have time, why don’t you help me? (a present/general fact)

So here, the teacher is talking about a situation after the main event (the class), so it’s future and hypothetical → future subjunctive: tiver.

Could you say se você ainda tem alguma dúvida instead? Would that be wrong?

You can hear se você ainda tem alguma dúvida in informal spoken Brazilian Portuguese, and people will understand you. But in standard/educated Portuguese, this is usually considered less correct or less natural in this context.

Se você ainda tiver alguma dúvida, pode perguntar depois da aula. ✅ (preferred)
Se você ainda tem alguma dúvida, pode perguntar depois da aula. 😐 (informal / sounds a bit off in careful speech)

Because the doubt will exist later, after the explanation, Brazilian Portuguese strongly prefers the future subjunctive (tiver) after se for this kind of future possibility.

What exactly does ainda mean here?

Ainda most often means still or yet, depending on context. Here it has the sense of still:

Se você ainda tiver alguma dúvida…
If you still have any questions…

It implies:

The teacher expects that some doubts may remain even after the explanation.
You might already have doubts now, and after the class you may still have some.

Other uses of ainda:

Eu ainda moro lá. – I still live there.
Você não terminou ainda? – Haven’t you finished yet?

Can I move ainda and say se você tiver ainda alguma dúvida?

That word order is possible but sounds unnatural in this sentence. Native speakers almost always put ainda in front of tiver here:

✅ Se você ainda tiver alguma dúvida… (natural)
❌ Se você tiver ainda alguma dúvida… (grammatically possible, but odd / stiff)

General rule of thumb for this kind of sentence: keep ainda before the verb phrase:

Se você ainda tiver dúvidas…
Se você ainda estiver com dúvida…

Why is it alguma dúvida and not uma dúvida or qualquer dúvida?

All three exist, but they have slightly different nuances:

Alguma dúvida
Literally: some doubt. Here it works like any question. It’s neutral and very common:
- Se você ainda tiver alguma dúvida…
  If you still have any questions…
Uma dúvida
Literally: a doubt / one doubt. It tends to sound like you’re expecting a specific or single doubt:
- Se você tiver uma dúvida específica, pode falar comigo.
  If you have a specific question, you can talk to me.
Qualquer dúvida
Literally: any doubt whatsoever. It emphasizes “no matter what it is”:
- Qualquer dúvida, é só me chamar.
  Any questions at all, just call me.

In the teacher’s sentence, alguma dúvida is the most natural, neutral choice.

Does dúvida mean exactly the same as English doubt?

Not exactly. Dúvida can mean doubt, but in many everyday situations it really means question.

Você tem alguma dúvida?
= Do you have any questions? (in a class, a meeting, etc.)

So in educational or informational contexts:

dúvida → often better translated as question.
ter dúvida sobre algo → to be unsure / to have a question about something.

English doubt (as in I doubt that’s true) is more like:

duvidar de algo – to doubt something
e.g. Eu duvido que isso funcione. – I doubt this will work.

Why is it pode perguntar and not an imperative like pergunte?

In Portuguese, using poder (can/may) in the present tense is a very common way to give a polite invitation or permission, softer than a direct command.

Você pode perguntar depois da aula.
= You can / may ask after class. (polite, neutral)

A direct imperative with você:

Pergunte depois da aula.
= Ask after class. (sounds more like an order; can be fine, but less soft.)

Teachers usually want to sound encouraging rather than bossy, so pode perguntar works like “feel free to ask”.

Why doesn’t it say pode me perguntar? Who are we supposed to ask?

By default, from context, it’s clear that you will ask the person speaking (the teacher). Portuguese often omits the object when it’s obvious:

Se você ainda tiver alguma dúvida, pode perguntar depois da aula.
The understood meaning is: “you can ask me”.

You can add the indirect object if you want to be explicit:

…pode me perguntar depois da aula. – you can ask me after class.
…pode perguntar para mim depois da aula. – more informal, but common.

But it’s not required; the original sentence is perfectly natural.

Do we have to say você, or could it just be se ainda tiver alguma dúvida…?

You can drop você:

Se ainda tiver alguma dúvida, pode perguntar depois da aula.

This is grammatical and sounds fine, especially if it’s obvious you’re talking to the listener.

In Brazilian Portuguese, people often include você to make it sound direct and clear:

Se você ainda tiver alguma dúvida… (very common, friendly, explicit)
Se ainda tiver alguma dúvida… (a bit more neutral/impersonal)

Both are correct; the version with você is just more explicit.

What does depois da aula literally mean, and why da instead of de a?

Depois = after (as an adverb).
A aula = the class / the lesson.
De + a contracts to da in Portuguese.

So:

depois da aula
literally: after of-the class → after class / after the class.

Contraction rule:

de + a → da
de + o → do
de + as → das
de + os → dos

So you say:

depois da aula – after the class
depois do filme – after the movie

Is there a difference between depois da aula and após a aula?

They are very similar in meaning: both can mean after class.

Depois da aula
– More common in everyday speech.
– Slightly more informal/neutral.
Após a aula
– A bit more formal or written style.
– Used a lot in notices, rules, instructions, or formal writing.

In casual speech, a teacher is much more likely to say depois da aula.

Why is the first verb in the future subjunctive (tiver) but the second verb just present (pode perguntar) even though it’s about the future?

Portuguese often uses this pattern:

Future subjunctive in the if-clause (condition).
Present (or future) in the main clause.

Example:

Se chover amanhã, a gente cancela a viagem.
If it rains tomorrow, we cancel the trip. (= we will cancel)

Similarly:

Se você ainda tiver alguma dúvida, pode perguntar depois da aula.
Literally: If you still have any doubt, you can ask after class.
Meaning: If you still have any questions then, you *will be able to / may ask after class.*

English needs future in the main clause (you can/will be able to), but Portuguese is fine using the present pode to refer to future permission/possibility in this structure.