One of the most common GMAT errors in Sentence Correction will require you to fix run-on sentences. A run-on sentence contains more than one independent clause that is not properly joined. It’s important to remember that you can’t combine two independent clauses with a comma. For example:
Ruth and Jack saw “Avatar”, I decided to go see “The Hurt Locker.”
Because we have two complete thoughts in this sentence, it is grammatically incorrect to separate them with only a comma. Here are a few possible ways to correctly separate two independent clauses:
Add a period. The simplest fix is to make the clauses two separate sentences.
Ruth and Jack saw “Avatar.” I decided to go see “The Hurt Locker.”
Add a conjunction. Another way to correct this error is to add a conjunction between the two clauses. It’s important to remember that if you add a conjunction, you will need to keep the comma. The comma will always go BEFORE the conjunction.
Ruth and Jack saw “Avatar,” but I decided to go see “The Hurt Locker.”
FANBOYS is an easy acronym to remember the coordinating conjunctions: for, and, nor, but, or, yet, so.
Add a semi-colon. If you see an answer choice that adds a semi-colon, you will often want to start there. The semi-colon will simply replace the comma. It’s often the most concise way to correct a run-on.
Ruth and Jack saw “Avatar”; I decided to go see “The Hurt Locker.”
Add a colon. A colon can sometimes be used to separate two independent clauses if the first sentence introduces a list, an explanation, or a quote. This wouldn’t work with our example sentence, so let’s modify it slightly.
Ruth and Jack were anxious to see some of the latest movies: “Avatar,” “The Hurt Locker,” and “A Single Man.”
Add a dash. A dash could also potentially be used if the second independent clause indicates a change in thought. An example would be:
Ruth and Jack saw “Avatar” – or was it “The Hurt Locker”?
The key to correctly identifying and correcting this error is to pay attention to any comma used in a GMAT Sentence Correction. Always check to make sure the clauses on each side of the comma aren’t independent. If they are, you’ll need to find the answer choice that employs one of the above corrections without introducing a new error or changing the meaning of the sentence.