Use a question mark [ ? ] at the end of a direct question. It is considered bad form to use a question mark in combination with other marks, although that is often done in informal prose in an attempt to convey complex tones: He told you what!? That combination (or similar combination) of punctuation marks is called an interrobang, but the interrobang currently has no role in academic prose.
A tag question is a device used to turn a statement into a question. It nearly always consists of a pronoun, a helping verb, and sometimes the word not. Although it begins as a statement, the tag question at the end requires the use of a question mark. Notice that when the statement is positive, the tag question is expressed in the negative; when the statement is negative, the tag question is positive. (There are a few exceptions to this, frequently expressing an element of surprise or sarcasm: “So you’ve made your first million, have you?” “Oh, that’s your plan, is it?”) The following are more typical tag questions:
- He should quit smoking, shouldn’t he?
- They’re not doing very well, are they?
- He finished on time, didn’t he?
Be careful not to put a question mark at the end of an indirect question.
- The instructor asked the students what they were doing.
- I wondered if my sister had a date.
Be careful to distinguish between an indirect question, and a question that is embedded within a statement, which we do want to end with a question mark.
- We can get to Toronto quicker, can’t we, if we take the 401?
- His question was, can we end this statement with a question mark?
- She ended her remarks with a resounding why not?
Put a question mark at the end of a sentence that is, in fact, a direct question. Rhetorical questions (asked when an answer is not really expected), by the way, are questions and deserve to end with a question mark:
- How else should we end them, after all?
- What if I said to you, “You’ve got a real problem here”? (Notice that the question mark here comes after the quotation mark and there is no period at the end of the statement.)
Sometimes a question will actually end with a series of brief questions. When that happens, especially when the brief questions are more or less follow-up questions to the main question, each of the little questions can begin with a lowercase letter and end with a question mark.
- Who is responsible for executing the plan? the coach? the coaching staff? the players?
If a question mark is part of an italicized or underlined title, make sure that the question mark is also italicized:
- My favorite book is Where Did He Go?
(Do not add a period after such a sentence that ends with the title’s question mark. The question mark will also suffice to end the sentence.) If the question mark is not part of a sentence-ending title, don’t italicize the question mark:
- Did he sing the French national anthem, la Marseillaise?
When a question ends with an abbreviation, end the abbreviation with a period and then add the question mark.
- Didn’t he use to live in Washington, D.C.?
When a question constitutes a polite request, it is usually not followed by a question mark. This is especially true as the request becomes longer and more complex:
- Would everyone in the room who hasn’t received an ID card please move to the front of the line.