1. Perhaps the most common error occurs when an independent clause states a problem and follows it with an order or directive. A student writes, ?he trip will be expensive, you should take a lot of money with you. Correction: "The trip will be expensive. You should take a lot of money with you."
Other correction possibilities:
a. "The trip will be expensive; you should take a lot of money with you."
b. "The trip will be expensive, so you should take a lot of money with you."
When you use a comma to connect two independent clauses, you have to follow it with a conjunction (and, but, for, nor, yet, or, so).
2. Another error occurs when two independent clauses are connected by a transitional expression such as however, moreover, nevertheless. "The Olympic team is lacking one key person, nevertheless, they expect to do well in the try-outs." Again correction possibilities call for the use of either a period or a semi-colon in place of the first comma.
a. "The Olympic team is lacking one key person. Nevertheless, they expect to do well in the try-outs."
b. "The Olympic team is lacking one key person; nevertheless, they expect to do well in the try-outs."
Unless the sentences are fairly short, it is usually better to make two separate sentences.
3. A third common error occurs when the second of two independent clauses begins with a pronoun. "I love my new computer class, it is so interesting." Although these independent clauses are short and are definitely related, the sentence is still a run-on. The clauses need to be separated with a full stop or a semi-colon. Here you could also connect them with because. "I love my new computer class because it is so interesting."
What do you need to remember in order to avoid problems with run-on sentences? First, neither the length of two clauses nor their degree of relatedness determines whether or not a sentence is a run-on. Second, avoiding run-on sentences does matter if you want to express yourself clearly. Running your thoughts together on paper can be just as confusing to a reader as speaking without pauses. Third, if you want to avoid problems with run-on sentences or with sentence fragments, you need lots of practice. Here are two links to practice exercises on the Internet: http://webster.commnet.edu/grammar/runons.htm and http://webster.co mmnet.edu/grammar/fragments.htm. Both are from an excellent site, Guide to Grammar and Writing. Read the information about both types of sentence boundary problems. Then scroll down the page to the quizzes.