Montgomery College Germantown Campus

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Common Grammar & Punctuation Mistakes

Common Grammar & Punctuation Mistakes

  Wrong word
  Missing comma after an introductory element
  Incomplete or missing documentation
  Vague pronoun reference
  Spelling (includes homonyms)
  Mechanical error with a quotation
  Unnecessary comma
  Unnecessary or missing capitalization
  Missing word
  Faulty sentence structure
  Missing comma with a nonrestrictive element
  Unnecessary shift in verb tense
  Missing comma in a compound sentence
  Unnecessary or missing apostrophe (including its/it’s)
  Fused (run-on) sentence
  Comma splice
  Lack of pronoun-antecedent agreement
  Poorly integrated quotation
  Unnecessary or missing hyphen
  Sentence fragment

Lunsford, A. (2011). The St. Martin’s Handbook. Boston, MA: Bedford/St. Martin’s.

Punctuation Rules

For more details on commas, semicolons, and apostrophes, see our Punctuation page here.

a.      Introductory phrases, transitions, and dependent clauses
                                                              i.      In the meantime, Idgy sliced tomatoes.
                                                           ii.      However, she sliced her finger as well.
                                                         iii.      Because she sliced her finger, Idgy retrieved a bandage.
b.      Items in a series of three or more (the Oxford comma)
                                                              i.      I need to buy apples, oranges, and bananas.
c.       Interrupting and additional information
                                                              i.      Thomas Edison, a famous inventor, was born in 1847.
                                                           ii.      He invented the light bulb, for which he is quite well-known.
d.     Two independent clauses joined by conjunctions (FANBOYS)
                                                              i.      I love green figs, so I purchase them whenever they’re in season.

A semicolon joins two complete sentences (independent clauses) in order to show a direct relationship.                                                             
 Example:      I love MCthe best professors on Earth work here.

Quotation Marks

    1. Place on both sides of direct quotes 
      1. First rule: Do not use semicolons, as Kurt Vonnegut said.
    1. Commas and direct quotes
      1. According to my mother, “The barn is like a second home!”
    1. Punctuation marks go inside of quotation marks
      1. “Life is beautiful!”  OR  “Life is beautiful.”  OR  “Life is beautiful?”
    1. Place a period after the in-text citation when integrating a direct quote
      1. “I like the music because it’s the sound of things flying apart” (Rollins, p. 168).
    1. Possession: singular and plural
      1. Nick’s, Brooks’s = singular
      2. parents’ = plural
    1. Contractions
      1. don’t, can’t, won’t, shouldn’t, I’m
    1. Compound adjectives
      1. mother-in-law, twelve-year-old, fixer-upper                                                              

Grammar Mistakes

1.      Homophones: words that sound alike but are spelled differently and have different meanings.
a.      it’s and its, there and their, affect and effect, then and than
2.      Pronoun-antecedent mismatch: when an antecedent is singular and the pronoun is plural or vice versa.
a.      “Where Does a Student Look for Their Books?”
b.    Some people do not recognize this as a pronoun-antecedent mismatch because it allows the sentence to remain gender-neutral. Keep in mind the audience you're writing for and, if submitting to a publication, any style guides. 
3.      Vague pronoun references: when a pronoun does not clearly replace its antecedent (subject noun).
a.      Josh and Drew are best friends, so he is at his house all the time.
4.      Shifts in verb tense: changing from past to present tense, for example.
a.      “Priya was watching the great blue heron. Then she slips and falls into the swamp” (Lunsford).
5.      Missing and unnecessary capitalization
a.      My favorite television show is the walking dead on amc .
b.      My Dad bought a cool Bike at a Convention in Baltimore.
6.      Sentence boundaries
a.      Run-on or fused sentence: when two complete sentences (independent clauses) are fused together without punctuation.
                                                              i.      This burger is delicious   I could eat two of them!
b.      Fragments can occur when a subject or a verb is missing from an independent clause. There are also:
                                                              i.      Dependent word fragments
1.      Although, I really like this burger.
                                                           ii.      -ing and to fragments
1.      Eating this burger with lots of ketchup.
                                                         iii.      Added-detail fragments
1.      This burger is delicious. Especially with sautéed mushrooms!