Editing Common Comma Errors

In the last lesson, you learned how to combine sentences to improve the flow of your writing. In this lesson, you'll review how to avoid three common comma errors that can occur when you combine sentences.

1. Missing Comma in a Compound Sentence: When you combine two sentences (independent clauses) using a coordinating conjunction (and, but, or, nor, for, so, yet), always place a comma before the conjunction.

   Manuel gave swimming lessons to Sam, and Lupita coaxed him into the wave pool.

   Note: Without the comma, this compound sentence could be misread as "Manuel gave swimming lessons to Sam and Lupita . . .

2. Missing Comma in a Series: Use commas to separate three or more words, phrases, or clauses, in a series.

   I want to thank my parents, Spock, and Serena Williams.

   Note: Without the final comma, this sentence could be misread as "I want to thank my parents, Spock and Serena Williams (the parents are Spock and Serena Williams?).

3. Missing Comma After Long Introductory Phrases or Clauses: Place a comma after a long introductory phrases or clauses before the main part of sentence.

   In the middle of the night, the neighborhood was usually very quiet.

   When I heard a thump and shout, the pounding of my heart filled the room.

   Note: Without the comma, the opening clause gets confused with the subject: "a thump and shout the pounding of my heart . . ."