Interrogative pronouns are always used to ask a question. In most cases, they do not have an antecedent (the noun to which the pronoun refers) because the pronouns essentially stand in for the answer to the question. They represent what is unknown. In the English language, there are five main interrogative pronouns. “Who” and “whom” refer to a person, “what” refers to a thing and “which” refers to a person or thing. “Whose” is an possessive pronoun that refers to a person. The suffixes of “-ever” and “-soever” are also added to these pronouns in some cases. Interrogative pronouns are never plural and ask a question that usually requires more than an answer of “yes” or “no.”
Keep in mind that some interrogative pronouns are also relative pronouns; the difference lies in the context of the sentence and whether a question is asked. Relative pronouns are sometimes within a question; interrogative ones are always within one.
“Who” refers to a person, and it changes its form depending on the case. When “who” is the subject of the verb, use the subjective case. Consider the following example:
Example: Who opened the refrigerator? (“Who” is the subject of the verb “opened.”)
When “who” is used with verbs in the passive form, use the subjective case of “who.” Passive verbs are always “to be” verbs (is, am, was, were, be, been) alone or followed by the past participle of the main verb, or they are a linking verb. When a verb is passive, the subject is the main part of the sentence, but the action is performed by something other than the subject. Consider the following example:
Example 1: Who was embarrassed the most? (“Was” is a form of “to be,” and “embarrassed is the past participle form of “embarrass.”)
Example 2: Who is dancing? (“Is” is a form of “to be.”)
Example 3: Who is there? (“Is” is a linking verb in this case because it is the only verb in the sentence).
When “who” is the object of the verb or the preposition, you must use the objective case “whom.” Consider the following examples:
Example 1: Whom did you see in Hollywood? (“Whom” is the object of the verb “see.”)
Example 2: To whom did you send the itinerary? (“Whom” is the object of the preposition “to.”)
Sometimes the interrogative pronoun “whose” is used as a possessive pronoun, where it implies possession belonging to the noun or pronoun that answers the questions. Consider the following example:
Example 1: I found Jim’s luggage. Whose did you find? (Answer: I found his luggage, or I found Ken’s luggage.)
The use of “what” versus “which” is sometimes confusing. When “what” is used to ask a question, there are limitless possibilities for an answer. On the other hand, “which” is used to ask a question when you are choosing between two items or when the number of answers is limited. Consider the following examples:
Example 1: What movie did you go to see last night?
In this case, “what” is used because the answers are essentially unlimited. The answers to this question could include indicating the time of the movie (the 9:30 p.m. showing), the theatre (the one at the AMC theatre) or the title of one of many movies (“The Girl with the Dragon Tattoo” or “The Muppets”).
Example 2: Which boots should I wear with this skirt – my brown ones or my black ones?
In this case, “which” is the determiner used before the noun “boots,” and the answer is limited to two choices. Even if the second portion of the sentence omitted, the use of “which” implies that the number of answers is limited, as most women would not have an unlimited number of boots.
Interrogative pronouns that begin a sentence in order to answer a question are called direct questions. In a direct question, when the interrogative pronoun is the subject of a verb, the verb follows the subject. Consider the following example:
Example: What happened yesterday? (“What” is the subject of the verb “happened.”)
The use of the interrogative pronoun “what” makes the sentence a question; therefore, a question mark is needed for punctuation.
Interrogative pronouns are sometimes used at the beginning of indirect questions and are part of a longer sentence. Consider the following example:
Example: Can you tell me who was invited? (“Who” is the subject that precedes the verb “was invited,” and “who was invited” is an indirect question that is part of a longer sentence.)