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Period

The end of a complete sentence should be marked by a period, a question mark, or an exclamation point. If a sentence is not complete and it is terminated by a period, we have a sentence fragment as in the sentence below.

Incorrect: You can use any resources. To complete your take-home exam.

Correcting the Problem

Correct: You can use any resources to complete your take-home exam.

Rule to Remember

The end of a complete sentence should be marked by a period, a question mark, or an exclamation point.

Sentence fragments are discussed in a different section of this tutorial. This section will explore the uses of punctuation marks used to mark the end of sentences.

End of Sentence

A period is used to signal the end of a complete sentence.

Correct: This is the best paper I've ever written.

A period is also used at the end of an indirect question.

Correct: The teacher asked us if we understood the assignment.

Polite requests can be followed either by a period or by a question mark.

Correct: Will you please mail this letter for me.
Correct: Will you please mail this letter for me?

Abbreviations

A period should be placed after every part of the abbreviation:

A.D. Dr. Watson
a.m. (am is also possible) Ave.

Very common abbreviations and units of measure don't take periods:
mph mp3
rpm mpg

Academic degrees can be written with or without periods:
DDS EdD
M.S. B.A.

Lower case abbreviations are usually written with periods: i.e.
Government agencies and international organizations are written without periods:
FBI UNESCO
UN NATO
UNICEF EU

Question Mark

Direct questions are followed by a question mark.

Correct: The teacher asked, "Do you understand the assignment?"

Exclamation Point

Exclamatory sentences should be followed by an exclamation point.

Correct: Wow! That's incredible!

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