How well do you know your question marks?
How often do you find yourself using an interrogation point in your everyday writing? What about an eroteme? You might be surprised to know that both of these appeared in the last two sentences. These terms might be unfamiliar, but you may know this punctuation mark by its more common name: the question mark. The question mark has a very simple function in writing—it indicates a question. If a sentence ends with a question mark, then it is asking a question, just as the name suggests.
How common is a question mark?
A sentence ending in a "?" is also known as an interrogative sentence. This means that its function is to pose a question to readers. You've likely seen them used in all types of writing, from fiction writing to nonfiction writing and from academic writing to personal writing. Indeed, it is one of the more widely used punctuation marks. In documents where an exclamation point is inappropriate, there is nothing wrong with using a question mark.
Question marks replace commas
You might be surprised to know that the question mark, while used exclusively to ask questions, can function in some rather unique situations, the most surprising being its ability to stand in for a comma. Take this sentence, for example:
"Where is Eric's car? and where is he, for that matter?" asked Sarah.
This is a grammatically correct use of the question mark. It might look awkward to some, but the laws of grammar state that when multiple questions are asked in the same sentence, a "?" can be used in place of a comma to indicate multiple questions. This should, however, only be done in works of fiction, primarily in dialogue.
Question marks in screenplays
A second application that writers may not be familiar with, and that is applicable only in non-formal situations, is the rhetorical question mark. It is used almost exclusively in screenplays, in order to indicate intended sarcasm. It is written in parentheses at the end of the sentence (?). This lets the actor know that the tone is sarcastic.
Adam: "Hey, Mr. McCabe, what was I supposed to do with the ion transducer?"
Charles: "Do I really need to tell you twice, Johnson! (?)"
Question marks in formal and informal writing
Question marks are used in both formal and non-formal writing and in cases where direct and indirect questions are being asked. They are one of the few pieces of punctuation that indicate only one thing. Placing a question mark at the end of a sentence that is not explicitly asking a question will instantly make it an awkward sentence. On the other hand, you can put an exclamation mark at the end of almost any sentence and render it exciting (albeit often out of context). For example:
"Go to the store and get me five apples!"
This sounds like the speaker is very excited about getting apples.
"Go to the store and get me five apples?"
This makes the speaker sound unsure about the amount of apples they want, making for an awkward sentence.
Question marks are generally reserved for sentences that begin with, or at least contain, why, what, when, where, how, are, will, is, can, how, do, were, or would:
"Will you go to the store with me?"
"Are you going to Rome this weekend?"
"How does that electric can opener work?"
"Can I have your extra toaster?"
Remember, a basic rule to follow when writing is if your sentence is asking a question, it must finish with a question mark. Failing to punctuate it properly will likely be noticed and cause confusion. Readers will almost always pick up on missing question marks, as written questions are often very distinct.