Run-on sentences are incorrectly punctuated sentences and often interfere with the meaning and clarity of a student's writing. Simply stated, the run-on sentence consists of two or more sentences run together as one, either with no punctuation or with a comma where a period or semicolon should go. Run-on sentences may be incorrectly punctuated in the following ways:
A run-on exists when two sentences are punctuated as if they were one. This mistake is also known as a fused sentence when there is no punctuation.
A comma alone is not considered sufficient punctuation between two main clauses, or clauses that can stand independently. This error is called a comma splice.
Each sentence must contain at least one subject-verb core, as shown in the following sentence patterns:
Note: Compound sentences consist of two independent clauses. Usually, a comma or semicolon precedes a coordinate conjunction, depending on the conjunction used.
Note: Sometimes the semicolon substitutes for the coordinate conjunction and joins the two independent clauses.
Note: Paired conjunctions like "either-or" and "not only but also" form a basic different compound sentence pattern. To be considered coordinate conjunctions each half of the pair must be followed by a subject verb core.
"Debbie will go" is the first subject-verb core. "David will meet" is the second subject-verb core following the paired conjunction.
"Delegation did reach" is the first subject-verb core. "They brought" is the second subject-verb core following the paired conjunction.
Exceptions are sentence patterns that use "you understood," begin with expletives like "there," or ask questions.
Complex sentences contain a main or independent clause connected to a subordinate or dependent clause by a subordinate conjunction.
The subordinate or dependent clause contains a subject and verb as well, but the connector or subordinate conjunction sometimes acts as both a conjunction and subject of the clause.
The main clause comes first followed by the subordinate clause.
The word "who" is a subordinate conjunction, and it also acts as subject of the dependent clause. Note that no punctuation comes before the subordinate conjunction here.
The subordinate clause comes first and the main clause follows. A comma indicates that the usual order of the clauses has been reversed.
"While" is the subordinate conjunction and introduces the subordinate or dependent clause: "while he went to the gym."
If more than one subject-verb core is contained in one sentence, the proper punctuation mark and conjunction must be present. Often a coordinate conjunction is needed.
Subordinate clause introduced by "who" interrupts the main clause: "who met at a fraternity party."
The subject "Debbie, David, and Daniel" is separated from its verb "studied" by the subordinate clause.
Commas are needed around the subordinate clause separating the subject from the verb.
Coordinate conjunction "but" joins the two main clauses: "Debbie, David and Daniel studied philosophy together" and "they could not agree about their philosophies of life."
The subordinate clauses introduced by "who" and "whenever," in this example, precede the coordinate conjunction "but" that joins the two main clauses.
In a complex sentence the subordinate conjunction may correctly be at or near the beginning of the sentence.
Subordinate clause introduces the sentence and the entire clause acts as subject of a sentence: "That you do not like philosophy" is known as the noun clause to the verb "is." The subordinate conjunction is "that."