Three marks can signal the end of a sentence: the period, the exclamation point, and the question mark.
| 20a | Use a period to end a declarative sentence, a directive, or an indirect question |
Most sentences are declarative, meaning that they make a statement.
Most people on earth are malnourished.
A period, not a question mark, ends an indirect question, which states that a question was asked or is being asked.
The counselor asked Marcia why she rarely gets to class on time.
I wonder why Roland didn’t show up.
Written as direct questions, those sentences require a question mark.
The counselor asked, “Marcia, why do you rarely get to class on time?”
Why, I wonder, didn’t Roland show up?
| 20b | Use a period after some abbreviations |
A period within a sentence shows that what precedes it has been shortened.
Dr. Robert A. Hooke’s speech will be broadcast at 8:00 p.m.
For more on abbreviating names, see 28e.
The names of many organizations (YMCA, PTA), countries (USA, UK), and people (JFK, FDR) are abbreviated using all capitals without periods. Other abbreviations, such as those for designations of time, use periods. When an abbreviation ends a sentence, follow it with one period, not two.
| 20c | Use a question mark to end a direct question |
How many angels can dance on the head of a pin?
For advice on punctuating indirect quotations and questions, see 25a. For examples of indirect questions, see 20a.
The question mark comes at the end of the question even if the question is part of a longer declarative sentence.
“What’ll I do now?” Marjorie wailed.
It can indicate doubt about the accuracy of a number or date.
Aristophanes, born in 450(?) BC, was a master comic playwright.
Often the same purpose can be accomplished more gracefully in words:
Aristophanes, born around 450 BC, was a master comic playwright.
In formal writing, avoid using a question mark to express irony or sarcasm: her generous (?) gift. If your doubts are worth including, state them directly: her meager but highly publicized gift.
| 20d | Use an exclamation point to end an interjection or an urgent command |
Rarely used in college writing, an exclamation point signals strong emotion.
We’ve struck an iceberg! We’re sinking! I can’t believe it!
It may mark an interjection or emphasize an urgent directive.
Oh, no! Fire! Hurry up! Help me!