Both qué and cuál may be used with the verb ser, but each elicits a different type of answer. When qué is used in front of ser, it requests an explanation or a definition; cuál is used with ser to request a specific example:
- Question: ¿Qué es la dirección? (asks for an explanation of the word dirección)
- Answer: La dirección es el número y nombre de la calle, la ciudad y el estado y el código postal.
- Question: ¿Cuál es la dirección? (asks for a specific address)
- Answer: La dirección es 322 Altavista Lane, Sante Fe, New Mexico.
Prepositions in questions
In Spanish, you may not end a sentence in a preposition, so the question word “where” must have any preposition in front of it, rather than at the end of the sentence. It is quite common to end a question about origin with a preposition in English: “Where is he from?” for example. The Spanish equivalent of, “Where is he from?” must be stated, “From where is he?” ( ¿De dónde es él?).
The same is true for the preposition a (which means “to”). Sometimes, this preposition is not stated in an English sentence, but any time the question asks where a noun is headed (such as “Where are you going to?”), the word dónde must have a in front of or attached to it (¿A dónde vas tú? or ¿Adónde vas tú?).
Remember that the prepositions por and para have distinct uses. One reason for using por is to express “due to” or “because of.” When a question is asking for a response that will provide the reason behind something, por qué is used because it asks “why?” (as in “due to what reason?”).
- ¿Por qué conduces el coche de tu hermano?
- Why (due to what reason) are you driving your brother's car?
One reason for using para is to indicate the purpose for doing something. When the question “why” is asking, “For what purpose?” use the question phrase para qué:
- ¿Para qué sirve esta herramienta? Sirve para arreglar las botellas.
- For what does this tool serve? It serves to fix the bottles.
- ¿Para qué estudia Emi? Ella estudia para pasar su examen.
- Why is Emi studying? She is studying to pass her exam.
The personal a is used when the direct or indirect object of a sentence is a word that refers to a person.
- To whom did he [she, formal you] throw the ball?
To indicate the possessor of an item in Spanish, the item is followed by the preposition de and the owner. To request this information, de is followed by the question words quién or quiénes, depending on whether you expect the owner to be one person or more. The English equivalents are “Whose?” or “Of whom?”:
- ¿De quién es el Pontiac azul en el aparcamiento?
- Whose is the blue Pontiac in the parking lot?
- ¿De quiénes son esos coches en la esquina?
- Of whom are those cars on the corner? (assuming the answer is more than one person)
The good news is that the question words cuándo (when?) and cómo (how?) are basically used the same in Spanish as in English.