Periods with Parenthetical Documentation
People generally know that they have to put a period at the end of a sentence. However, sometimes it’s hard to tell where the sentence ends.
Errors with Comma Splices
Incorrect: In order to strengthen a sprained ankle, the girl exercised in the gym daily, however, her ankle remained weak.
These are actually two sentences and should have a period between them. As is, this is a comma splice run-on: two sentences spliced together with a sentence.
Corrected: In order to strengthen a sprained ankle, the girl exercised in the gym daily. However, her ankle remained weak.
In short, closely related sentences such as these, a semi-colon could also be used between the sentences.
Also Correct: In order to strengthen a sprained ankle, the girl exercised in the gym daily; however, her ankle remained weak.
Although semi-colons separate words group that can stand alone as sentences (independent clauses), semicolons are not considered end punctuation since they are used within a sentence, not to end a sentence.
Errors with Fused Run-Ons
Similarly, sometimes there is no punctuation to end the sentence resulting in a fused run-on.
Incorrect: In order to strengthen a sprained ankle, the girl exercised in the gym daily however, her ankle remained weak.
There must be a period or a semi-colon separating the sentences.
Errors with Extra Periods
Sometimes, periods are inserted into the middle of a sentence where they don’t belong.
Incorrect: In order to strengthen a sprained ankle, the girl exercised daily. But the ankle remained weak.
The period does not belong there since the words following the period are not a sentence and are part of the previous sentence.
Corrected: In order to strengthen a sprained ankle, the girl exercised daily, but the ankle remained weak.
Here’s another example how determining the end of a sentence can sometimes be confusing.
Incorrect: She went to the store, then, she went to the gym.
These are two sentences separated by a comma just as with the previous example.
Words such as however, then, and now are sometimes in the middle of a sentence and sometimes at the beginning of a sentence.
Corrected: She went to the store, then to the gym.
Now, since these are no longer two sentences, there is no need for a period.
Periods with Abbreviations
Periods are also used in some abbreviations. When an abbreviation which has a period is used at the end of a sentence, don’t use a period to end the sentence. There should not be a double period at the end of a sentence.
I asked her to come at 10 a.m.
Periods with Quotation Marks
When there is a period next to an end quotation mark, the period goes before the end quotation mark, not after it.
“The explorers were stranded in the most unbearable conditions.” See how the period is before the end quotation mark.
Periods with Parenthetical Documentation
Parenthetical documentation is documentation or citing or the source in parentheses. When there is parenthetical documentation at the end of the sentence, the period goes only after the parentheses. The parenthetical documentation is part of the sentence.
“The explorers were stranded in the most unbearable conditions” (Chu). See how the period goes only after the parentheses.
Question marks are used at the end of questions. When there is a question mark, there should not also be a period since the question mark is the end punctuation.
When there is a quote, if the quote is a question, then the question mark goes inside the quotation marks:
He asked, “Who is going?”
Sometimes, there is a question about whether a sentence contains a direct question.
He asked about who is going.
With this phrasing, there is no direct question. It is an indirect question.
Question marks can also be used for rhetorical questions – questions used for persuasion.
The earth has been gradually warming since the end of the last Ice Age. Are humans really speeding up this warming trend or is it just part of the natural process?
An exclamation point is used to show strong emphasis or importance.
“Put down the box!” the woman yelled.
Ordinarily, we would use a comma to separate out the words that say who says a quote (a signal tag). However, a comma is not used next to an exclamation point.
Exclamation points are rarely used in research writing. When it is used in a direct quote, only one exclamation point is used. Don’t add additional exclamation points to be more emphatic.