What follows are explanations of some of the most common grammar and punctuation errors. This is not meant to be an exhaustive list, but rather an overview of a few rules that seem to give student writers the most trouble. It is a good idea to become familiar with the rules of grammar that you violate most frequently so that you can begin to search for those particular errors when you edit your papers. I've noted the appropriate sections and page numbers in our book, Rules for Writers, for each type of error.

Common comma errors

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Missing comma after introductory phrases (Section 32b--page 295)

For example: After the devastation of the siege of Leningrad the Soviets were left with the task of rebuilding their population as well as their city. (A comma should be placed after "Leningrad.")

No comma in nonrestrictive relative clauses (Section 32e--pages 299-303)

Here you need to distinguish between a restrictive relative clause and a nonrestrictive relative clause. Consider the sentence, "My brother in the red shirt likes ice cream." If you have TWO brothers, then the information about the shirt is restrictive, in that it is necessary to defining WHICH brother likes ice cream. Restrictive clauses, because they are essential to identifying the noun, use no commas. However, if you have ONE brother, then the information about the shirt is not necessary to identifying your brother. It is NON-RESTRICTIVE and, therefore, requires commas: "My brother, in the red shirt, likes ice cream."

Missing comma in a series (Section 32c--page 297)

Whenever you list things, use a comma. You'll find a difference of opinion as to whether the next-to-last noun (the noun before the "and") requires a comma. ("Apples, oranges, pears, and bananas...") Our advice is to use the comma because sometimes your list will include pairs of things: "For Christmas she wanted books and tapes, peace and love, and for all the world to be happy." If you are in the habit of using a comma before the "and," you'll avoid confusion in sentences like this one.

Missing comma in a compound sentence (Section 32a--page 294)

For example: Wordsworth spent a good deal of time in the Lake District with his sister Dorothy and the two of them were rarely apart. (Comma should be placed before the "and.")

Run-ons & Comma Splices

Comma splice (Section 20a--pages 196-201)

A comma splice occurs when two independent clauses are joined only with a comma. For example: ”Picasso was profoundly affected by the war in Spain, it led to the painting of great masterpieces like Guernica." A comma splice also occurs when a comma is used to divide a subject from its verb. For example: "The young Picasso felt stifled in art school in Spain, and wanted to leave." (The subject "Picasso" is separated from one of its verbs "wanted." There should be no comma in this sentence, unless you are playing with grammatical correctness for the sake of emphasis -- a dangerous sport for unconfident or inexperienced writers.)

Fused sentence (Section 20a--pages 195-201)

Fused sentences are sentences that run on forever, they are sentences that ought to have been two or even three sentences but the writer didn't stop to sort them out, leaving the reader feeling exhausted by the sentence's end which is too long in coming. (Get the picture?) Fused sentences occur when two independent clauses are put together without a comma, semi-colon, or conjunction. For example: "Researchers investigated several possible vaccines for the virus then they settled on one."

Sentence Fragments (Section 19a--pages 188-195)

Silly things. To be avoided. Unless, like here, you are using them to achieve a certain effect. Remember: Sentences traditionally have both subjects and verbs. Don't violate this convention carelessly.

Colons, Semi-colons, and Dashes

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Colons (Section 35a--pages 317-319) : If you know how to use a colon correctly, it can add complexity and variety to your writing. The main rule to remember is that a colon applies only in certain situations: Use a colon after an independent clause (a complete sentence) to direct attention to a list, an appositive, or a quotation. The colon is NOT the same as a semicolon. Don’t mix them up; don’t use them interchangeably.

Semi-colons (Section 34a--pages 313-317) ; the semi colon is often misused because students think it is like a comma; it is not. It does not pause but rather it stops. Use the semi-colon between closely related independent clauses (complete sentences) NOT joined with a coordinating conjunction (for, and, nor, but, or, yet, so). The semi-colon is actually more like a period than a comma.

Dashes (Section 39a--pages 332-333) – Use a dash when you really want to emphasize something—parenthetical material, for example. Note that you type two hyphens to form a dash (--) and you don’t put spaces before or after the dash.

Apostrophes (Section 36a--pages 319-323) '

Sometimes apostrophes are incorrectly left out (Mikes book, Sylvias hat); other times, they are incorrectly put in (her's, their's, etc.)

Pronoun Errors

Ambiguous pronoun reference (Section 23a--pages 218-222)

For example: The boy and his father knew that he was in trouble. (Who is in trouble? The boy? His Father? Some other person?)

Pronoun/antecedent agreement error (Section 22a--pages 213-218)

Many students have a problem with pronoun agreement. They will write a sentence like "Everyone is entitled to their opinion." The problem is, "everyone" is a singular pronoun. You will have to use "his" or "her."

Tense shift (Section 13b--pages 148-149)

Be careful to stay in a consistent tense. Too often students move from past to present tense without good reason. This is distracting and can confuse your reader.

Unnecessary shift in person (Section 13a--pages 147-148)

Don't shift from "I" to "we" or from "one" to "you" unless you have a rationale for doing so.

Quotation Marks (Section 37a--pages 323-329)

There are many rules for the correct use of quotation marks. Here are some of the basics: 1) use quotation marks to enclose titles of short works, 2) place periods and commas INSIDE quotation marks, 3) only use single quotation marks when you are enclosing a quotation within a quotation.

You will also need to be aware of how to integrate a quotation into a paper. You should never drop a quotation, but need to introduce it with a signal phrase. For example, the following quote is introduced correctly. Montaigne writes, “I quote others in order to better express my own self.” It would be wrong if the signal phrase (Montaigne writes) was not included. Look back at Lesson 5's Essay Writing Tip--Integrating Quotations (The Technical Aspect) for further details.

Wrong word

Its often hard too spot wrong word errors, but there often their! Proofread carefully and read your paper allowed. This way, you will be able to see when you use a word like “allowed” instead of “aloud” or “too” instead of “to” or “there” instead of “they are” and "their" instead of "there."

Italics

The MLA dictates that italicizing be used rather than underlining. The key is to be consistent and to know the rules. A general rule of thumb: longer works are generally italicized (novels rather than short stories). The shorter works are generally put in quotation marks.

When reading your papers for grammar errors, you'll want to make note of a few things:

First, determine whether the error is a matter of carelessness or a pattern of error. If you find a single run-on in your paper, there's probably not much to worry about. Fix it, and be on your way. But if you notice that you tend to run on again and again, it's time to think about the run-on. Do you understand the boundaries of the sentence? Do you understand the grammatical principles at work in determining these boundaries? If you think that you don't, consult a tutor and/or a handbook. Come up with strategies for addressing the problem so that it doesn't occur in future drafts.
Second, prioritize among your errors. If you find that your grammar problems are serious ones, determine which of the problems are most serious and address them first. Problems that interfere with a reader's understanding of your paper -- misplaced modifiers, for example, or mistakes in punctuation -- ought to be addressed first. If you have trouble determining which mistakes are most serious, visit the Writing Center. Our tutors can help you to map a course of study in matters of grammar.
Third, practice writing sentences. The only way to learn to write grammatically is to practice, practice, practice. Grammar exercises do help. Just remember to take your time, work slowly, and think carefully about what you are doing. Grammar is complicated and needs careful attention to be understood well.
Finally, understand that grammar COUNTS. Your professors expect writing that is correct. Papers that are full of errors are difficult to read and may affect the overall meaning of your paper. A paper full of errors also suggests a rushed effort or a lack of attention to the final product. It is your responsibility to master the rules of the language that you speak and write. Learn them well.