Some students believe that a run-on sentence is simply a very long sentence that goes on and on. That is not so. A sentence may be quite long and still be correct. What, then, is a run-on sentence? A run-on sentence is one in which two (or more) sentences have been run together without a proper join.

There are only two correct ways of joining sentences: one is to use a comma with a coordinating conjunction; the other is to use a semicolon.

A conjunction is a joining word. Coordinating conjunctions are words that join things of equal value, such as two nouns, two verbs, two phrases, or two sentences.

There are seven coordinating conjunctions: for, and, nor, but, or, yet, and so. The key word fanboys, formed from the first letters of these seven conjunctions, will help you to remember them.

Two sentences can be joined properly using a comma and a coordinating conjunction.

Examples: Alison went to the library to study, and Jennifer went to the gym.

The driver was exhausted, so he fell asleep at the wheel.

We missed our flight, for our tickets had been stolen.

Ryan could not fasten his bindings, nor could he find his ski poles.

(Note that in each example, the comma comes before the coordinating conjunction.)

Using a Semicolon

If you do not use a joining word between sentences, then you must use a semicolon (;).

A semicolon is like a period in that it makes a full stop between sentences. However, there is a difference. If you use a period, you have begun a new sentence and must capitalize the first word after the period. If you use a semicolon, you have put both sentences together into one, and you do not capitalize the first word after the semicolon, unless it requires capitalization for some other reason.

Examples: Alison went to the library to study; Jennifer went to the gym.

We missed our flight; our tickets had been stolen.

Sometimes the connection between the two sentences may seem too abrupt if only a semicolon is used. In that case, you may wish to use a semicolon with a conjunctive adverb. (Note that a comma is used after the conjunctive adverb.)

Examples: Alison went to the library to study; meanwhile, Jennifer went to the gym.

The driver was exhausted; as a result, he fell asleep at the wheel.

If you attempt to join sentences without using either of these two correct methods, you will have a run-on sentence, which is a serious error in sentence structure.

Examples:

(a) The driver was exhausted he fell asleep at the wheel.

Error: The two sentences have simply been run together with no join of any sort. (This type of error is called a fused run-on.)

(b) Alison went to the library to study and Jennifer went to the gym.

Error: The conjunction and has been used without a comma.

(c) We missed our flight, our tickets had been stolen.

Error: A comma has been used without a conjunction. The comma should be replaced with a semicolon, or a conjunction should be added. (This type of run-on is called a comma splice.)

(d) The driver was exhausted, as a result he fell asleep at the wheel.

Error: Here is another example of a comma splice. A comma has been used with a conjunctive adverb; the comma should be replaced with a semicolon, or a conjunction should be added.

1. My twin brother Mark and I are both tall, slender blondes and look very much alike, however any resemblance between us ends there.
2. Mark is an avid sportsman he likes to ski, golf, jog, and play tennis.
3. In contrast, I am entirely non-athletic, my daily exercise is walking between the house and the bus stop.
4. Mark is a health nut; he eats only vegetarian meals low in fat and he never eats junk.
5. However, I love all kinds of junk food, in fact, I could survive on a steady diet of chocolate, potato chips, and pop.
6. When he is not being physically active, Mark likes to spend his quiet time reading and writing poetry.
7. I spend my quiet time watching television or talking on the phone to my friends but I hardly ever open a book or a magazine.
8. Mark is an introvert, therefore he likes activities that he can do by himself.
9. I, on the other hand, am an extrovert so I have plenty of friends who unfortunately distract me from solitary pursuits like reading and studying!
10. To those who know us, Mark and I are incredibly different; it is hard to believe that we are twins.

ANSWERS

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