Grammar Mechanics: GED Test Prep

Updated on Jul 5, 2011

When do you need a comma? When should you use a dash or semicolon? How do you know when something should be capitalized? These questions and more will be answered in this article. You will review the basic rules of mechanics so that you can answer GED Language Arts, Writing questions about spelling, capitalization, and punctuation.

Mechanics refers to the rules that govern punctuation marks, capitalization, and spelling. Like the rules that govern usage, the rules that govern sentence mechanics help us keep our sentences and their meanings clear.

Since the GED Language Arts, Writing Exam was revised in 2002, the only spelling that is tested is the spelling of homonyms, possessives, and contractions. Correct use of punctuation will be tested, but comma questions will generally be limited to instances where a comma is necessary to eliminate or prevent confusion.


Punctuation marks are the symbols used to separate sentences, express emotions, and show relationships between objects and ideas. Correct punctuation makes your meaning clear and adds drama and style to your sentences. Poor punctuation, on the other hand, can lead to a great deal of confusion for your readers and can send a message other than the one you intended. For example, take a look at the following two versions of the same sentence:

    Don't bother Xavier.
    Don't bother, Xavier

These sentences use the same words, but have very different meanings because of punctuation. In the first sentence, the comma indicates that the speaker is telling the reader not to bother Xavier. In the second sentence, the speaker is telling Xavier not to bother. Here's another example of how punctuation can drastically affect meaning:

    You should eat Zak so you can think clearly during your interview.

Because this sentence is missing some essential punctuation, the sentence says something very different from what the author intended. The speaker isn't telling the reader to eat Zak; rather, she's telling Zak to eat. The sentence should be revised as follows:

    You should eat, Zak, so you can think clearly during your interview.

Punctuation helps to create meaning, and it also has another important function: It enables writers to express a variety of tones and emotions. For example, take a look at these two versions of the same sentence:

    Wait—I'm coming with you!
    Wait, I'm coming with you.

The first sentence clearly expresses more urgency and excitement thanks to the dash and exclamation point. The second sentence, with its comma and period, does not express emotion; the sentence is neutral.

Punctuation Guidelines

There are many rules for punctuation, and the better you know them, the more correctly and effectively you can punctuate your sentences. The following table lists the main punctuation marks and guidelines for when to use them:

Comma Rules

Many mechanics questions will deal with commas, the most common punctuation mark within sentences. The presence and placement of commas can dramatically affect meaning and can make the difference between clarity and confusion. The previous chart lists four comma uses, but there are several others. What follows is a complete list of comma rules. If you know them, then you can be sure your sentences are clear. You will also be able to tell whether or not a comma is needed to correct a sentence.

Use a comma:

  1. with a coordinating conjunction to separate two complete sentences. Note that a comma is not required if both parts of the sentence are four words or less.
      Let's eat first, and then we will go to a movie.
      I'm definitely older, but I don't think I'm much wiser.
      I love him and he loves me.
  2. to set off introductory words, phrases, or clauses.
      Next year, I will stick to my New Year's resolutions.
      Wow, that sure looks good!
      Because the game was canceled, Jane took the kids bowling.
  3. to set off a direct address, interjection, or transitional phrase.
      Well, Jeb, it looks like we will be stuck here for a while.
      His hair color is a little, um, unusual.
      My heavens, this is spicy chili!
      Sea horses, for example, are unusual in that
      the males carry the eggs.
  4. between two modifiers that could be replaced by and.
      He is a mean, contemptible person.
      (Both mean and contemptible modify person.)
      Incorrect: Denny's old, stamp collection is priceless.
      Correct: Denny's old stamp collection is priceless.
      (You cannot put "and" between old and stamp; old describes stamp and stamp modifies collection. They do not modify the same noun.)
  5. to set off information that is relevant but not essential (nonrestrictive).
      Essential, not set off:
      The woman who wrote Happy Moon is coming to our local bookstore.
      (We need this information to know which woman we're talking about.)
      Nonessential, set off by commas:
      The dog, lost and confused, wandered into the street.
      (The fact that the dog was lost and confused is not essential to the sentence.)
    • Essential, not set off:
      Witnesses who lie under oath will be prosecuted.
      Nonessential, set off by commas:
      Leeland, who at first refused to testify, later admitted to lying under oath.
  6. to separate items in a series.
      The price for the cruise includes breakfast, lunch, dinner, and entertainment.
      The recipe calls for fresh cilantro, chopped onions, diced tomatoes, and lemon juice.
  7. to set off most quotations. As a general rule, short quotations are introduced by commas while long quotations (several sentences or more) are introduced by colons. All speech in dialogue should be set off by commas.
      "Let's get going," he said impatiently.
      Rene Descartes is famous for the words, "I think, therefore I am."
      Joseph said, "Please forgive me for jumping to conclusions."
  8. to set off parts of dates, numbers, titles, and addresses.
      She was born on April 30, 2002.
      Please print 3,000 copies.
      Tiberio Mendola, MD, is my new doctor.
      Please deliver the package to me at 30 Willow Road, Trenton, NJ.
  9. to prevent confusion, as in cases when a word is repeated.
      What it is, is a big mistake.
      After I, comes J.
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