Mi sobrina es muy curiosa y siempre pregunta por qué.

Mi means my. It is a possessive adjective, so it shows who the niece belongs to in the family relationship: mi sobrina = my niece.

You would use:

• la sobrina = the niece
• una sobrina = a niece
• mi sobrina = my niece

In Spanish, possessive adjectives like mi, tu, su, nuestro usually come before the noun.

Because sobrina is the feminine form and means niece.
Sobrino is the masculine form and means nephew.

So:

• mi sobrina = my niece
• mi sobrino = my nephew

This is a normal masculine/feminine noun pair in Spanish.

Es is the he/she/it form of the verb ser in the present tense.

The sentence is describing a characteristic of your niece: she is very curious. For identity and general qualities, Spanish usually uses ser.

So:

• Mi sobrina es muy curiosa = My niece is very curious.

Adjectives in Spanish often agree with the noun they describe in gender and number.

Since sobrina is feminine singular, the adjective must also be feminine singular:

• sobrina curiosa
• not sobrina curioso

Compare:

• Mi sobrino es muy curioso = My nephew is very curious.
• Mi sobrina es muy curiosa = My niece is very curious.

Muy means very. It intensifies the adjective curiosa.

So:

• curiosa = curious
• muy curiosa = very curious

A useful rule:

• muy goes before adjectives and adverbs
• mucho/mucha/muchos/muchas is usually used with nouns

For example:

• muy curiosa = very curious
• mucha curiosidad = a lot of curiosity

Y means and. It connects the two parts of the sentence:

• Mi sobrina es muy curiosa
• siempre pregunta por qué

So the whole sentence links two ideas:

1. she is very curious
2. she always asks why

Siempre means always.

In this sentence, it comes before the verb:

• siempre pregunta = always asks

That is a very common position in Spanish. Adverbs like siempre often go before the main verb, though word order can vary for emphasis.

Examples:

• Siempre llega temprano = He/She always arrives early.
• Siempre pregunta por qué = She always asks why.

Preguntar is the infinitive, meaning to ask.
Pregunta is the present tense form meaning he/she asks.

Since the subject is mi sobrina, you need the third-person singular present:

• yo pregunto = I ask
• tú preguntas = you ask
• él/ella pregunta = he/she asks

So:

• Mi sobrina pregunta = My niece asks

Por qué is used in direct and indirect questions and means why.

In this sentence, pregunta por qué means asks why. Even though there are no question marks, it is still an indirect question, so Spanish uses por qué.

Compare:

• ¿Por qué preguntas? = Why are you asking?
• Ella pregunta por qué. = She asks why.

This is a very common question in Spanish.

• por qué = why

  • used in questions, direct or indirect
  • Pregunta por qué. = She asks why.

• porque = because

  • used to give a reason
  • Pregunta porque tiene curiosidad. = She asks because she is curious.

• porqué = the reason

  • usually used as a noun, often with el
  • No entiendo el porqué. = I do not understand the reason why.

• por que

  • less common as a separate combination
  • appears in certain structures, such as luchar por que... or with verbs/adjectives that require por
    • que

In your sentence, the correct form is por qué because it means why.

Qué has a written accent when it is used in interrogative or exclamatory meaning, including indirect questions.

Since por qué here means why, it takes the accent:

• pregunta por qué

Compare:

• No sé qué quiere. = I do not know what he/she wants.
• El libro que leo = The book that I am reading.

In the second example, que has no accent because it is not interrogative.

Yes, if the subject is already understood from context.

Spanish often leaves out subject pronouns and even full noun subjects when they are clear:

• Siempre pregunta por qué. = She always asks why. / He always asks why.

But in your sentence, mi sobrina is included because the speaker wants to identify who is being described.

Spanish often drops subject pronouns because the verb ending already shows the person.

• pregunta already tells you it is he/she/it
• the noun mi sobrina makes it even clearer that the subject is she

So Spanish normally says:

• Mi sobrina es muy curiosa not
• Mi sobrina ella es muy curiosa

Adding ella would usually sound unnecessary unless you want special emphasis or contrast.

No. English ask can translate as more than one verb in Spanish.

• preguntar = to ask a question
• pedir = to ask for something

In your sentence, the niece is asking why, so she is asking a question:

• pregunta por qué

Compare:

• Pregunta la hora. = She asks the time.
• Pide agua. = She asks for water.

Yes. Usually curioso/a means curious or inquisitive, but depending on context it can also mean interesting, odd, or strange.

Here, because it is followed by siempre pregunta por qué, the meaning is clearly curious/inquisitive.

So the sentence suggests she is the kind of child or person who always wants to know the reason for things.

In most of Spain, z and soft c are pronounced with the th sound from English think. But this sentence does not contain z or soft c in curiosa.

A few useful pronunciation notes:

• sobrina: stress on bri
• curiosa: stress on rio
• siempre: stress on siem
• pregunta: stress on gun
• qué: stressed because it is a question word

In standard Spain pronunciation:

• curiosa has an s sound, not a th sound
• por qué sounds roughly like por KEH

Usually, no, not in this context.

• ser is used for general characteristics: She is curious as part of her personality.
• estar is used more for states or conditions.

So:

• Mi sobrina es muy curiosa = she is a curious person by nature

If you said está curiosa, it would sound unusual here and could suggest a temporary state or a different nuance depending on context. For a personality trait, es is the natural choice.

The given word order is the most natural and neutral one:

• Mi sobrina es muy curiosa y siempre pregunta por qué.

Spanish does allow some flexibility, but changes in word order often create emphasis or a more literary tone.

For everyday speech, the original order is exactly what a learner should aim for.