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10.05: Run-ons, fragments, comma splices

  • Page ID
    25431
    • Alexandra Glynn, Kelli Hallsten-Erickson & Amy Jo Swing
    • North Hennepin Community College & Lake Superior College

    As we discussed, complete sentences, or independent clauses, contain a subject, a verb, and form complete a thought:

        The big, brown cow walked quickly and quietly away.

    The subject is “cow,” the verb is “walked.” The other words modify or give more information about other words.

    What is a sentence fragment?

    Fragments occur when the sentence is missing the subject and/or verb and/or it’s an incomplete thought:

    Walked quickly and quietly away towards the rabbit.

    There is no subject in this group of words. What or who walked? Notice that the word “rabbit” is a noun and can, in its own sentence, be the subject. But in this case, it is part of the prepositional phrase that tells where the walking is towards. Thus, it cannot be the subject, even though it is a noun.

    Because the big, brown cow walked quickly and quietly away.

    The addition of the subordinating conjunction “because” creates an incomplete thought.

    Other words that create fragments when added to the beginning of sentences include other subordinating conjunctions and coordinating conjunctions (lists of these are at the end of the section). These are words that turn levers in brains to indicate some sort of connection is coming, like a trailer with a hitch. That part of the sentence needs something with an engine (main subject and governing verb) to hook up to before it can go anywhere. It needs a simple sentence (independent clause) to hitch to.

    Sentence fragments are fixed by either adding the missing words or hooking the fragment onto a sentence that comes before it or after it in the paragraph.

    The big brown cow walked quickly and quietly away.

    Because the big, brown cow walked quickly and quietly away, I didn’t need to run away in terror from it.

    In the above examples, the main (simple) subject is underlined, and the verb is in italics. In the second sentence, “cow” is no longer the subject, because the word “because” has come in and made that whole clause from “because” to “away” into a dependent clause, a trailer, needing a hitch.

    What is a run-on sentence?

    Run-on sentences happen when two complete sentences (independent clauses) are put together incorrectly:

    I walked down to the store the heat was getting to me.

    “I walked down to the store” is a perfectly fine sentence. “The heat was getting to me” is another great sentence. Put them together, though, without proper punctuation, and you have a run-on.

    If you separate these two complete sentences with a comma, you have a type of run-on called a comma splice:

    I walked down to the store, the heat was getting to me.

    The comma is probably not strong enough to hold two sentences together. Why is this? There are logical, common sense reasons for it. One, certainly, is that since “store” is a noun, and “heat” is a noun, if there is no comma, the reader is left wondering what exactly the relationship is between “store” and “heat.” This is because nouns can modify (give information about) other nouns. Once you put in the comma, you immediately take away the possible question in the readers mind about what the relationship might be between “the store” and “the heat” because the comma indicates, sort of, “new thought starting here.” The reader knows that the noun “the heat” is the subject of something, starting a whole new section of the sentence. Again, this all proves yet another time that a sentence is a series of logical-grammatical relationships that people’s brains are programmed at birth to know and follow.

    How to fix a run-on sentence

    So, if I do have a run-on sentence, which is basically a sentence that doesn’t easily make sense, how do I fix it? There are options. Use a coordinating conjunction:

    I walked down to the store, for the heat was getting to me.

    …or use a subordinating conjunction:

    I walked down to the store since the heat was getting to me.

    …or use a semicolon:

    I walked down to the store; the heat was getting to me.

    …or use a conjunctive adverb with a semicolon:

    I walked down to the store; indeed, the heat was getting to me.

    …or go ahead and use a period.

    I walked down to the store. The heat was getting to me.

    One of the most common run-on sentences is this type:

    As I walked down to the store the heat was getting to me.

    It’s a run-on because it starts with a subordinating conjunction (again, words like because, since, when, and if) and does not have a comma separating out the two sentences. It should look like this:

    As I walked down to the store, the heat was getting to me.

    Some instructors will also call the clause, “As I walked down to the store” an introductory phrase that needs a comma after it. Whatever the instructor calls it, the comma needs to be there.

    List of coordinating conjunctions: List of common subordinating conjunctions: List of common conjunctive adverbs:
    For Because Also
    And If However
    Nor Since Indeed
    But When Nonetheless
    Or While Otherwise
    Yet As Consequently
    So Before Besides
      Wherever Ineed
      Once Moreover
      After Similarly
      Although Still
      Even (if, though) Likewise
      Unless Furthermore
      Until Hence
      Where Nevertheless
        Next
        Therefore
        Thus
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