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PART 4 PUNCTUATION

14. END PUNCTUATION

One of the most common uses of a period is to signal the end of a declarative sentence. A declarative sentence makes an assertion.

Sarah will pilot the plane.

A period should appear at the end of a sentence that includes an indirect question. An indirect question conveys the idea of a question without asking it directly, typically by stating that a question was or is being asked.

Julio asked if Sarah will pilot the plane.

A period can also indicate that the word preceding it has been abbreviated, or shortened. When an abbreviation ends a sentence, follow it with just one period.

Sarah G. Stein will fly the plane at 10:00 P.M., and the flight lasts for 2 hrs.

Abbreviations of units of time or measurement also use periods. However, most organizational names (PTA for Parent Teacher Association), place names—such as countries (USA for United States of America), airports (LGA for La Guardia Airport), or states (NY for New York)—and people’s names (MLK Jr. for Martin Luther King Jr.) are abbreviated with capital letters without periods.

Use a question mark to signal the end of a direct question. A direct question asks for information. It might ask for a yes or no response, elicit information, or echo a statement in question form.

Where will the plane land?

Sometimes a direct question can express doubt, irony, or sarcasm.

Sarah will pilot the plane?

Avoid using question marks to signal doubt in formal writing by rephrasing the indirect question as a declarative sentence (e.g., I am fairly sure that Sarah will pilot the plane). You should also avoid using question marks that express irony and sarcasm—instead, express your thoughts directly (e.g., Sarah’s dubious talent for flying aircraft makes me hesitant to take this trip).

An exclamation point can interject, create emphasis, and express strong emotion. Inserting one at the end of a sentence will change the tone—and sometimes the meaning—of a given assertion, question, or command.

Oh no! This is horrible! I can’t believe this happened! Our vacation is ruined!

Tornado! Find shelter!

It is best to use exclamation points sparingly, especially in formal writing.