What are interrogative pronouns and how are they used in question formation?

Interrogative pronouns are a type of pronoun that are used to ask questions. They are used to inquire about a person, thing, or information. Interrogative pronouns include words such as "who," "whom," "whose," "what," "which," and "where."

In question formation, interrogative pronouns are used to replace the noun or noun phrase that would typically be the subject or object of the sentence. They help to form direct or indirect questions by indicating what information is being sought.

For example, consider the following sentences:

1. Who is coming to the party?
In this sentence, "who" is the interrogative pronoun that replaces the noun phrase "the person coming to the party." It is used to ask about the identity of the person.

2. What did you eat for breakfast?
Here, "what" is the interrogative pronoun that replaces the noun phrase "the food you ate for breakfast." It is used to ask about the specific item of food.

3. Which book should I read?
In this sentence, "which" is the interrogative pronoun that replaces the noun phrase "the book I should read." It is used to ask about a particular book among a set of options.

Interrogative pronouns can also be used in combination with other words to form more complex questions. For instance:

- Whose car is parked outside?
- Where did they go on vacation?

In summary, interrogative pronouns are used to ask questions and replace the noun or noun phrase that would typically be the subject or object of the sentence. They help to form direct or indirect questions by indicating what information is being sought.