Below you’ll find a comprehensive explanation of sentence structure, run-on sentences, and fragments taken from GALILEO, University System of Georgia GALILEO Open Learning Materials. You’ll want to review the material carefully! If you’re more of a visual person, you might find this youtube tutorial equally as useful:

Or a youtube video I made on sentence structure:

Compound Sentences: Joining Clauses with Coordination

A compound sentence consists of two independent clauses joined by coordination. Coordination connects the two clauses in a way that emphasizes both clauses equally. Consider these two sentences:

Original sentences: I spent my entire paycheck last week. I am staying home this weekend.

In their current form, these sentences contain two separate ideas that may or may not be related. Am I staying home this week because I spent my paycheck, or is there another reason for my lack of enthusiasm to leave the house? To indicate a relationship between the two ideas, we can use the coordinating conjunction so:

Revised sentence: I spent my entire paycheck last week, so I am staying home this weekend.

The revised sentence illustrates that the two ideas are connected. Notice that the sentence retains two independent clauses (I spent my entire paycheck; I am staying home this weekend) because each can stand alone as a complete idea.

Coordinating Conjunctions

A coordinating conjunction is a word that joins two independent clauses. The most common coordinating conjunctions are for, and, nor, but, or, yet, and so. Note that a comma precedes the coordinating conjunction when it joins two independent clauses.

Table of Coordinating Conjunctions

Tip

To help you remember the seven coordinating conjunctions, think of the acronym FANBOYS: for, and, nor, but, or, yet, so. Remember that when you use a coordinating conjunction to connect independent clauses, a comma should precede the conjunction. (Exception: the comma is sometimes left out when the clauses are short and closely related. Example: John drove and I gave directions.)

Conjunctive Adverbs

Another method of joining two independent clauses with related and equal ideas is to use a conjunctive adverb and a semicolon. Like coordinating conjunctions, conjunctive adverbs can join independent clauses and indicate a particular relationship between them, but conjunctive adverbs create a stronger break between the clauses than coordinating conjunction do. Read the following sentences:

Original sentences: Bridget wants to take part in the next Olympics. She trains every day.

Since these sentences contain two equal and related ideas, they may be joined using a conjunctive adverb. Now, read the revised sentence:

Revised sentence: Bridget wants to take part in the next Olympics; therefore, she trains every day.

The revised sentence explains the relationship between Bridget’s desire to take part in the next Olympics and her daily training. Notice that the conjunctive adverb comes after a semicolon that separates the two clauses and is followed by a comma.

The table below lists common conjunctive adverbs and demonstrates their function.

Table of Conjunctive Adverbs

Complex Sentences: Joining Clauses with Subordination

Subordination joins two sentences with related ideas by combining them into an independent clause (a complete sentence) and a dependent clause (a construction that relies on the independent clause, also called the main clause, to complete its meaning). While coordination allows a writer to give equal weight to the two ideas that are being combined, subordination enables a writer to emphasize one idea over the other. Take a look at the following sentences:

Original sentences: Tracy stopped to help the injured man. She would be late for work.

To illustrate that these two ideas are related, we can rewrite them as a single sentence using the subordinating conjunction even though.

Revised sentence: Even though Tracy would be late for work, she stopped to help the injured man.

In the revised version, we now have an independent clause (she stopped to help the injured man) that stands as a complete sentence, and a dependent clause (even though Tracy would be late for work) that is subordinate to the main clause. Notice that the revised sentence emphasizes the fact that Tracy stopped to help the injured man, rather than the fact that she would be late for work. We could also write the sentence this way:

Revised sentence: Tracy stopped to help the injured man even though she would be late for work.

The meaning remains the same in both sentences, with the subordinating conjunction even though introducing the dependent clause.

Tip

To punctuate sentences correctly, look at the position of the main clause and the subordinate clause. If a subordinate clause precedes the main clause, use a comma. If the subordinate clause follows the main clause, no punctuation is required. Exception: subordinate clauses that begin with conjunctions that indicate concession (see table below) are sometimes preceded by a comma, even when they follow the main clause.

Subordinating Conjunctions and Adverb Clauses

A subordinating conjunction is a word that joins a subordinate (dependent) clause to a main (independent) clause. Since the resulting subordinate clause modifies the verb in the main clause, the subordinate unit is called an adverb clause.

Relative Pronouns and Adjective Clauses

While an adverb clause modifies the verb in an independent clause, an adjective clause modifies a noun. The modified noun may function in the sentence in any number of ways. It may be a subject, complement, direct object, or the object of a preposition.

Consider the following:

Original Sentences: Jill and her friends camped near a silver mine. The mine had been abandoned for fifty years.

The second sentence modifies or tells about the silver mine, which is the object of a preposition (near) in the first sentence. We can turn the second sentence into a subordinate adjective clause and attach it to the first sentence.

Combined Sentences: Jill and her friends camped near a silver mine that had been abandoned for fifty years.

The adjective clause is highlighted in yellow. That replaces the original subject of the second sentence (The mine) to form a subordinate adjective clause, and the clause is then attached to the first sentence, which becomes the main clause. The relative pronoun in this example is that. Like subordinating conjunctions, relative pronouns are used to make a clause dependent (or subordinate). But unlike subordinating conjunctions, relative pronouns take the place of another word, just as other pronouns do. And unlike adverb clauses, which can be located either before or after a main clause, an adjective clause must be located immediately after the noun that it modifies. If this rule is not followed, the adjective clause becomes a misplaced modifier (see Misplaced Modifiers). The following words can all function as relative pronouns: who, whom, whose, which, that, when, where.

Restrictive and Nonrestrictive Adjective Clauses

An adjective clause is restrictive if it is essential for identifying (restricting) the noun that it modifies. A nonrestrictive clause may be important to the sentence, but it is not essential for identifying the noun. This distinction is important because nonrestrictive clauses must be set off from the main clause with commas. Consider these examples:

•   My brother Frank, who ran cross country in high school, beat everybody in the foot race.
•   A young man who ran cross country in high school beat everybody in the foot race.Both these sentences contain the same adjective clause (who ran cross country in high school), but in the first example the clause modifies a subject identified with a proper noun (Frank) and the designation my brother. Consequently, the adjective clause is not essential to the identification of the subject. It is nonrestrictive and set off with two commas, one before the clause and one after it.

  In the second example, the subject is simply “A young man.” Consequently, the adjective clause is necessary to the identification of who this particular young man is. The clause is restrictive and is not set off with commas (see comma use).

Common Errors: Fragments and Run-ons

Fragments

A fragment occurs when a group of words that does not form a complete sentence is punctuated as though it is a complete sentence. Here are three common types of fragments and ways to correct them:

The fragment may lack a predicate because the verb is incomplete:
Fragment: The runners staggering in the 100-degree heat.
Complete sentence: The runners were staggering in the 100-degree heat.

(Note: The present participle staggering is not a complete verb without the helping verb were. See Progressive Verb Tenses.)

The fragment may be a dependent (subordinate) clause that needs to be attached to an independent clause:

Fragment: Unless she could earn the money for tuition.
Complete sentence: Unless she could earn the money for tuition, she would have to drop out of school.
(Note: The fragment here is an adverb clause and does not express a complete thought unless it is attached to an independent clause. See Complex Sentences.) Fragment: Which was the best thing to do.

Complete sentence: My sister decided to sell the house, which was the best thing to do.

(Note: The fragment here is an adjective clause and does not express a complete thought unless it is attached to an independent clause. See Complex Sentences.)

The fragment may be a subject with modifiers that needs a linking verb.

Fragment: Doubt and mistrust everywhere, fogging the minds of managers and workers alike.

Complete Sentence: Doubt and mistrust were everywhere, fogging the minds of managers and workers alike.

(Note: Were supplies the needed linking verb in this sentence (see Sentence Patterns). Fogging may seem like a verb, but it is only part of a participial phrase and cannot be a complete verb without a helping verb. See Components of a Sentence.)

Run-on Sentences

Sentences with two or more independent clauses that have been incorrectly combined are known as run-on sentences. A run-on sentence may be either a fused sentence or a comma splice.

Fused sentence: A family of foxes lived under our shed young foxes played all over the yard.

Notice that there are two sentences here, one about a family of foxes, which ends with the word shed, and another about the young foxes. These two sentences are simply run together without any punctuation, coordination, or subordination, creating a fused sentence.

Comma splice: We looked outside, the kids were hopping on the trampoline.

Here the break between the two sentences is marked with only a comma. Since a comma is not a legitimate way to connect independent clauses, this creates a comma splice.

Correcting Run-ons with Punctuation

One way to correct run-on sentences is to correct the punctuation. For example, adding a period will correct the run-on by creating two separate sentences. Using a semicolon between the two complete sentences will also correct the error. A semicolon allows you to keep the two closely related ideas together in one sentence. When you punctuate with a semicolon, make sure that both parts of the sentence are independent clauses.

Run-on (fused sentence): The accident closed both lanes of traffic we waited an hour for the wreckage to be cleared.

Corrected sentence: The accident closed both lanes of traffic; we waited an hour for the wreckage to be cleared.

When you use a semicolon to separate two independent clauses, you may wish to add a conjunctive adverb to show the connection between the two thoughts. After the semicolon, add the conjunctive adverb and follow it with a comma (see Compound Sentences).

Run-on (comma splice): The project was put on hold, we didn’t have time to slow down, so we kept working.

Corrected sentence: The project was put on hold; however, we didn’t have time to slow down, so we kept working.

Coordinating conjunctions (remember FANBOYS) and subordination, discussed in the sections on Compound Sentences and Complex Sentences, can also be used to fix run- ons.

KEY TAKEAWAYS

• A sentence is complete when it contains both a subject and verb (predicate). A complete sentence makes sense on its own.
• Every sentence must have a subject, which usually appears at the beginning of the sentence. A subject may be a noun (a person, place, or thing) or a pronoun.
• A compound subject contains more than one noun.
• A prepositional phrase describes, or modifies, another word in the sentence but cannot be the subject of a sentence.
• A verb is often an action word that indicates what the subject is doing. Verbs may be action verbs (transitive or intransitive), linking verbs, or helping verbs.
• Remembering the five basic sentence patterns is useful when correcting grammar errors.
• Fragments and run-on sentences are two common errors in sentence construction.
•  Fragments can be corrected by adding a missing subject or verb or combining a dependent clause with an independent clause.
• Run-on sentences can be corrected by adding appropriate punctuation or using coordination or subordination.