Unit 34: Punctuation Part 2

In this unit, we will review some of the main punctuation rules that we have covered, and provide additional practice on punctuation for the Digital SAT.

Punctuation and Prepositional Phrases

This rule is simple, but requires you to be able to identify prepositions in a sentence. A prepositional phrase can never be broken apart from what it describes with any punctuation.

An example:

Dr. Emily Thompson, a renowned marine biologist, published her groundbreaking research on coral reefs in the Pacific Ocean, in 2012, launched a global initiative for ocean conservation, in 2014; and was awarded the International Environmental Achievement Award, in 2016.

This is a complex sentence with multiple prepositional phrases, but “in 2012” cannot be split off from the research it is describing. The sentence should not have the comma before that phrase.


  • Prepositional phrases split by punctuation usually “sound funny” to us – if something seems off, check to see if this rule is being violated.
End Punctuation

You may also see a question or two about the punctuation that ends a sentence. Let’s review some of these rules as well.


  • Usage:
    • To end a declarative sentence.
    • To indicate abbreviations.
  • Examples:
    • Correct: He finished his assignment on time.
    • Incorrect: Dr Smith is an expert in her field. Ph. D.

Question Marks

  • Usage:
    • At the end of a direct question.
  • Examples:
    • Correct: What time is the meeting?
    • Incorrect: I wonder what time the meeting is?

Exclamation Marks

  • Usage:
    • To express strong emotion or a command.
    • Used sparingly in formal writing.
  • Examples:
    • Correct: Watch out!
    • Incorrect: She got the job!


  1. Consider the context.
    • Understand the broader context in which the sentence appears. Does the author seem to be asking a rhetorical question? Is the sentence a statement as part of a larger argument or narrative?
  2. Test each option.
    • Plug in each punctuation option into the sentence and read it aloud. Does the sentence still convey the intended meaning with that punctuation?

Our brains are usually pretty good at identifying when sentences are declarative, interrogative, or exclamatory. Read the context around the sentence carefully and then test each answer option. Use process of elimination to determine which one sounds the best.

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