An interrogative sentence is simply a sentence that asks a question—that is, we use it when we interrogate someone for information. Interrogative sentences always end with question marks.
Forming interrogative sentences
When we make sentences into questions, we almost always use auxiliary verbs that are inverted with the subject. This is known as subject-verb inversion. For example:
- “Are you sleepy?”
- “Will she be coming to the party later?”
- “Have they finished their project yet?”
- “Do you like country or classical music better?”
We can also use question words (who, what, where, when, why, and how) to ask more nuanced questions, but we still use auxiliary verbs and subject-verb inversion. For instance:
- “What does the boss think about the proposal?”
- “When will we arrive?”
- “Who is coming to the play?”
In this last question, the subject is unknown, so it is represented by the word who (which does not invert with an auxiliary verb).
Using these constructions, we can create several different kinds of interrogative sentences.
There are four main types of interrogative sentences: yes/no questions, alternative questions, “Wh-” questions, and tag questions.
Yes/No questions are simply questions that can be answered with either "yes" or "no." These are exclusively formed with auxiliary verbs that are inverted with the subject—that is, they do not use question words. For example:
- “Are you registered to vote?”
- “May I borrow your pen?”
- “Do you speak French?”
- “If you miss the deadline for entry, will you still be able to compete?”
- “Is there enough food for everyone?”
Alternative questions, also known as choice questions, are questions that provide a choice among two or more answers. These choices might be explicitly stated in the question (identified by the coordinating conjunction or), or they might be implied by the context. We usually use inverted auxiliary verbs on their own for these questions, but they can also be formed using certain question words. For example:
- “Do you prefer apple juice or orange juice?”
- “Who won—New York or Boston?”
- “Do you live in the city, or the suburbs?”
- “Do you want cake, pie, or ice cream?”
- “How would you like your steak cooked?” (The implied choices would be rare, medium, or well done.)
“Wh-” questions (or question word questions) are questions that seek information by posing a question with a "wh-" question word (who, what, where, when, why, and how). These questions seek an open-ended answer that can be short or long, simple or complex—there is no expectation about how the person might respond.
Here are some examples:
- “Who is your favorite author?”
- “What is the capital of England?”
- “When will you be finished with this project?”
- “Where are you going for your summer vacation?”
- “Why haven’t you responded to Karen’s invitation yet?”
- “How did you get here?”
Tag questions are formed by adding a question as a “tag” onto the end of a declarative sentence. This “tag” is usually made of at least an auxiliary verb inverted with a subject, though it is sometimes just a single word. It is considered parenthetical, so we set it apart from the rest of the sentence with a comma.
Tag questions are often rhetorical, used to confirm an answer that the speaker already knows or believes to be the case. For example:
- “You’re not going to the party, are you?”
- “This isn't your hat, is it?”
- “That was the most delicious meal, wasn’t it?”
- “You can’t talk during the movie, OK?”
- “We’re going to the game, right?”
Other interrogative sentences
Some interrogative sentences consist of a declarative statement posed to someone as a question, such as:
- “You won?”
- “It ended just like that?”
Some questions can even be a single word. These are often “question words,” (e.g. What?, Why?, When?, etc.), but they can consist of other words as well. For example:
- Speaker A: “Sir, you need to move your car.”
- Speaker B: “Me?”
- Speaker A: “You didn’t eat all of your vegetables.”
- Speaker B: “So?”
- Speaker A: “Well?”
- Speaker B: “Hold on, I’m thinking!”
Some declarative sentences express uncertainty, but are not truly interrogative. These are known as indirect questions. For example:
- "I was wondering if you would like to go to the party with me."
This does not pose an actual question, so it is not an interrogative sentence.
In informal writing, it is very common to see these types of sentences end with a question mark. However, this shouldn’t be done, especially in formal or professional writing—the question mark should either be left out, or the sentence should be rewritten. For example, to change the sentence above from declarative to interrogative, we could say, “Would you like to go to the party with me?”