Tu sabes a resposta?

Portuguese doesn’t use an auxiliary verb like do to form yes/no questions.
The question is made simply by:

• using the normal present tense (sabes = you know), and
• adding a rising intonation in speech or a question mark in writing.

So:

• Tu sabes a resposta. = You know the answer. (statement)
• Tu sabes a resposta? = Do you know the answer? (question)

Same words, same order; only the intonation/punctuation changes.

Sabes is the present tense form of saber for tu (you, singular informal) in European Portuguese:

• eu sei – I know
• tu sabes – you know (informal, singular)
• ele / ela sabe – he / she knows
• você sabe – you know (more formal / distant singular)
• nós sabemos – we know
• vocês sabem – you know (plural)
• eles / elas sabem – they know

So with tu you must say tu sabes, not tu sabe. Tu sabe is ungrammatical.

Yes, you can, and that’s very common.

Portuguese often drops subject pronouns because the verb ending already shows who the subject is. Sabes clearly indicates tu, so:

• Tu sabes a resposta?
• Sabes a resposta?

Both mean Do you know the answer?
Leaving out tu is natural and frequent in European Portuguese, especially in speech. Using tu can add a bit of emphasis or help avoid ambiguity when context isn’t clear.

In European Portuguese:

• tu = informal you (singular), used with friends, family, children, and often among younger people. It uses 2nd person verb forms (e.g., tu sabes).
• você = more distant or sometimes slightly formal you (singular). It uses 3rd person verb forms (e.g., você sabe).

So:

• Tu sabes a resposta? – informal
• Você sabe a resposta? – more distant / polite (and in many parts of Portugal, a bit stiff or even cold in everyday use)

In Brazil, você is usually the default informal you, but in Portugal tu tends to be more common in informal situations.

Yes, but the nuance changes.

• Tu sabes a resposta? / Sabes a resposta? – neutral question.
• Sabes tu a resposta? – possible, but sounds more emphatic, rhetorical, or literary in modern European Portuguese, as if stressing you in contrast to someone else.

This kind of inversion is not needed for normal questions; it’s used for emphasis or in more formal / stylised language.

Here a is the feminine singular definite article, meaning the, not the preposition to.

• a resposta = the answer
  
  • a = the (feminine singular)
  • resposta = answer

So Tu sabes a resposta? literally means You know the answer?

You cannot normally drop the article here.
✗ Tu sabes resposta? is ungrammatical in standard Portuguese.

(There is another a in Portuguese that is a preposition meaning to, but that’s a different word, even though it looks the same.)

Portuguese has two common verbs for to know:

• saber – to know a fact, information, how to do something.
• conhecer – to be acquainted with / familiar with people, places, or things.

Examples:

• Sei a resposta. – I know the answer. (fact → saber)
• Sei onde ele mora. – I know where he lives. (information → saber)
• Conheço o João. – I know João. (I’m acquainted with him → conhecer)
• Conheço Lisboa. – I know Lisbon (I’m familiar with the city → conhecer)

Since an answer is a piece of information, saber is the correct verb:
Tu sabes a resposta? = Do you know the answer?

Use vocês (plural you) with the corresponding verb form sabem:

• Vocês sabem a resposta? – Do you (plural) know the answer?

If you’re already talking to a group, you can also drop vocês and just say:

• Sabem a resposta? – Do you guys know the answer?

The subject is clear from context and the plural verb ending -em.

For more formality or distance, especially when addressing someone older or in a professional context, you can use o senhor / a senhora:

• O senhor sabe a resposta? – Do you (sir) know the answer?
• A senhora sabe a resposta? – Do you (madam) know the answer?

These forms take 3rd person verb forms (sabe, not sabes), and they sound respectful and polite in European Portuguese.

In European Portuguese, in normal connected speech, sabes a often sounds like one unit because the final s of sabes links to the a:

• tu – roughly like too (often quite reduced in fast speech)
• sabes – SAH-besh (final -s like sh in many accents)
• a – uh (very short, often reduced)

When spoken quickly:
Tu sabes a resposta? → something like too SAH-besh uh r(e)sh-POH-stuh?

Key points:

• Final s in sabes can sound like sh.
• Vowels in short words like a tend to be reduced and very quick.

Yes. In writing, the only difference is the punctuation:

• Tu sabes a resposta. – You know the answer. (statement)
• Tu sabes a resposta? – Do you know the answer? (question)

In speech, the difference is in intonation:

• Statement: falling tone at the end.
• Question: rising tone at the end.

Portuguese relies on intonation and context rather than auxiliary verbs like do to distinguish these.

Yes. In informal speech, Sabes? (from Tu sabes?) can work as a discourse marker, similar to English you know?:

• Sabes, eu não tive tempo. – You know, I didn’t have time.
• Ele, sabes, nunca chega a horas. – He, you know, never arrives on time.

Here sabes doesn’t literally mean do you know an answer; it organizes the conversation or softens what you’re saying. Context and tone tell you which meaning is intended.