Basic Interrogative Words:
* ¿Qué? (What?): Used for things. "¿Qué es eso?" (What is that?)
* ¿Quién? (Who?): Used for people. "¿Quién es él?" (Who is he?)
* ¿Quiénes? (Who?): Plural of quién. "¿Quiénes son ellos?" (Who are they?)
* ¿Cuál? (Which?): Used for selecting from a group. "¿Cuál prefieres?" (Which do you prefer?)
* ¿Cuáles? (Which?): Plural of cuál. "¿Cuáles son tus favoritos?" (Which are your favorites?)
* ¿Cuánto? (How much?): Used for uncountable nouns. "¿Cuánto cuesta?" (How much does it cost?)
* ¿Cuánta? (How much?): Feminine singular form of cuánto. "¿Cuánta agua hay?" (How much water is there?)
* ¿Cuántos? (How many?): Used for masculine plural countable nouns. "¿Cuántos hermanos tienes?" (How many brothers do you have?)
* ¿Cuántas? (How many?): Used for feminine plural countable nouns. "¿Cuántas hermanas tienes?" (How many sisters do you have?)
* ¿Dónde? (Where?): "¿Dónde estás?" (Where are you?)
* ¿Cuándo? (When?): "¿Cuándo llegas?" (When are you arriving?)
* ¿Cómo? (How?): "¿Cómo estás?" (How are you?)
* ¿Por qué? (Why?): "¿Por qué lo hiciste?" (Why did you do it?)
* ¿Para qué? (What for?/Why?): "¿Para qué necesitas eso?" (What do you need that for?)
* ¿A quién? (To whom?/Whom?): "¿A quién le diste el regalo?" (To whom did you give the gift?)
* ¿De quién? (Whose?): "¿De quién es este libro?" (Whose book is this?)
Important Notes:
* Inversion: In most cases, a question in Spanish is formed by inverting the subject and verb, or using an interrogative word at the beginning and then inverting. However, in informal speech, intonation is often sufficient to signal a question without inversion.
* Accents: Notice that all Spanish interrogative words (except 'quién' and 'quiénes') usually appear with an accent mark at the beginning. This is crucial for distinguishing them from their non-interrogative counterparts.
* Gender and Number Agreement: Pay close attention to the gender (masculine/feminine) and number (singular/plural) agreement with cuánto/cuánta/cuántos/cuántas.
Understanding these words and how they're used is essential for forming correct and natural-sounding questions in Spanish.