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Academic Skills

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Academic Skills

Sentence Structure

Revising Sentence Fragments, Run-On Sentences, and Comma Splices

Introduction

You cannot write a paragraph clearly if you cannot write clear sentences. Clear sentences are well-ordered, well-constructed sentences. The two most common sentence structure errors in student papers are run-on sentences and sentence fragments.

  1. Independent Clauses and Simple Sentences
  2. Subordinate Clauses and Complex Sentences
  3. Compound Sentences
    1. Compound-Complex Sentences
  4. Common Sentence Errors
    1. Sentence Fragments
    2. Run-on Sentences and Comma Splices

A variety of sentence types will always be more interesting to your reader than using the same type and length repeatedly.


Independent Clauses and Simple Sentences

A sentence is made up of one or more clauses. To understand what a sentence is, it helps to understand what a clause is. To do that, you must understand what a subject and verb are.

Clause

A clause is a group of words that contains a subject and a verb. A clause may have other words besides these, but to be a clause, it must have the two.

Subject

A subject is usually a noun (person, place, thing, idea) or a pronoun (a word that substitutes for and refers to a noun: e.g. "he" for "Sam"). The subject of a sentence is the noun or pronoun that name who or what the sentence is about: 

Fish swim. (Fish is the subject.)

He wrote the letter. (He is the subject.)

Verb

A verb conveys action or "states of being or mind."

Fish swim. (Swim is the verb.)

He seems happy. (Seems is the verb.)  

It is not always easy to recognize verbs which convey states of being or mind, but they are some of the most used. Examples are: to be, to seem, to have, to appear.

Subject-Verb Order

In English, subjects usually come before verbs:

The battle rages

However, sometimes the subject comes after the verb:

In our neighbours' yard are two big maple trees.                                  

There are several books on the table.

Subject-Verb Order is often reversed or modified in questions:

Who are you?     

Are you going home this weekend?

In an "expletive construction," the subject follows the verb and the sentence begins with either "there is" or "there are."

There is a book on the table.

There are several books on the table.

Independent Clauses

An independent clause has a subject and a verb and can be a simple sentence. All of the above example sentences are independent clauses and simple sentences.


Compound Sentences

When two simple sentences are combined correctly to make one longer sentence, we call that sentence a compound sentence. There are three ways to do this:

1. Coordinating Conjunction

The seven coordinating conjunctions are

  1. and
  2. but
  3. or
  4. nor
  5. for
  6. yet
  7. so

Think "fanboys." Fanboys is made up of the first letter of each of the above conjunctions.

In a compound sentence, simple sentences become known as independent clauses; the two independent clauses together make up a compound sentence. The coordinating conjunction must be preceded by a comma when you want to join two independent clauses into a compound sentence. For example:

The joke was funny, and it was on me.

[Note the comma before the coordinating conjunction, "and."]

Coordinating conjunctions can be used for many different reasons, so you don't always need to put a comma before ‘and’. This rule applies only when you join two independent clauses to make a compound sentence. For example:

The joke was funny and was on me.

[Note there is no comma. Joke is the subject and the verb "was" is used twice.]

The first example is a compound sentence with two independent clauses joined by ‘and’. The second is a simple sentence consisting of one independent clause with one subject and two verbs (or one verb used twice). For the simple sentence, a comma before ‘and’ is unnecessary.

2. Semi-colon

Use a semi-colon to join two independent clauses. Yes, it is actually that easy. For example:

We rely on mobile technologies; network outages cause serious problems.

3. Semi-Colon and an Adverbial Connective

Writers often confuse coordinating conjunctions with other kinds of words, but only the fanboys have the power of coordinating conjunctions.

Other words and phrases can also be used to combine independent clauses and make compound sentences, but they also require a preceding semi-colon. For example:

The vote was close; nevertheless, the government prevailed.

[Note the semi-colon before the adverbial connective, "nevertheless."]

The comma which comes after ‘nevertheless’ in the example is optional, but the semi-colon is required. Words like these have several different names: sentence connectors, transitional words/phrases, conjunctive adverbs, adverbial connectives.

Some Adverbial Connectives:

Words: accordingly, also, besides, consequently, finally, first, furthermore, hence, however, indeed, instead, likewise, moreover, nevertheless, next, nonetheless, otherwise, second, similarly, still, then, therefore, thus

Phrases: all in all, as a result, as an illustration, for example, for instance, for this purpose, in addition, in any event, in contrast, in fact, in general, on the contrary, on the other hand, on the whole, that is, to illustrate

Compound-Complex Sentences

A compound-complex sentence consists of two or more independent clauses and one or more subordinate clauses. For example:

I like the look of Dalmatians; however, I suspect that they are too high-strung to be good pets.

It is helpful to identify the sentence elements in the preceding example:

  1. independent clause: I like the look of Dalmatians
  2. semi-colon and adverbial connective: ; however,
  3. subordinate clause with relative pronoun: I suspect that
  4. independent clause: they are too high-strung to be good pets.

This example follows a different pattern:

Since we rely on mobile technologies, network outages cause serious problems, and we lack necessary safeguards for citizens, businesses, and governments.

  1. subordinate clause: Since we rely on mobile technologies,
  2. independent clause: network outages cause serious problems
  3. comma and coordinating conjunction: , and
  4. independent clause: we lack necessary safeguards for citizens, businesses, and governments.

Subordinate Clauses and Complex Sentences

Subordinate Clauses

A subordinate clause has a subject and a verb, but it cannot stand alone as a sentence.  Subordinate clauses begin with certain words or short phrases called subordinating words (also known as dependent words, or subordinating/subordinate conjunctions). If a clause begins with a subordinating word, that clause is a subordinate clause and cannot stand alone as a sentence.

Subordinating words: after, although, as, as if, as long as, because, before, even if, even though, ever since, if, in order that, provided that, since, so that, than, that, though, unless, until, what, whatever, when, whenever, where, whereas, wherever, whether

Relative Pronouns are also subordinating words: that, which, who, whose, whomever, whom, whoever, whichever

Examples of subordinate clauses:

Although the weather didn't cooperate

As he was in a hurry

If you really want to go

who led the Metis in the North West rebellions

Subordinate clause must be attached to an independent clause. If it is not, it becomes a sentence structure error called a sentence fragment. The above examples of subordinate clauses are fragments; they can be corrected by combining each with an appropriate independent clause, and making complex sentences:

A complex sentence

The most important thing to remember about all subordinate clauses is that they cannot stand alone as sentences; they must be combined with an independent clause to form a complex sentence:

Although the weather didn't cooperate, we had a good time.

As he was in a hurry, he didn't stop to chat.

If you really want to go, you have my permission.

Louis Riel, who led the Metis in the North West rebellions, was hanged for treason.

Subordinate means of lesser importance. In a compound sentence, the clauses are both independent, and both the ideas they convey are given equal emphasis. In contrast, in a complex sentence, the idea in the subordinate clause is not given equal emphasis; that is why the writer chooses to put it in the subordinate clause, thereby emphasizing the idea of the independent clause.

Compare these two examples sentences: 

Although she was penalized for plagiarism, she was basically an honest person. [Correct sentence]

The writer of this sentence wants to emphasize the idea of the independent clause - that "she was honest," and to place less emphasis on the idea of the subordinate clause - that "she was penalized for plagiarism."

Although she was basically an honest person, she was penalized for plagiarism. [Correct sentence]

Here, the writer is emphasizing that “she was penalized for plagiarism" and placing less emphasis on the fact that "'she was basically honest." The difference between the two sentences is subtle but clear.

The subordinate clause can precede or follow the independent clause.

These are both correct complex sentences:

Although the weather didn't cooperate, we still enjoyed our picnic.

We still enjoyed our picnic although the weather didn't cooperate.

When the subordinate clause precedes the independent clause, it is followed by a comma; the comma isn't necessary when the subordinate clause follows the independent clause.


Sentence Fragments

  1. Subordinate clause that stands alone
  2. Missing subject or verb

Remember that every independent clause must have a subject and a verb and that every sentence must have at least one independent clause. Any group of words written that does not have both a subject and a verb is a sentence fragment.

For example:

Had never eaten so much [no subject]

Being nervous [no subject]

The chips and beer [no verb]

Correcting Sentence Fragments

  1. Connect subordinate clause to independent clause to make a complex sentence.
  2. Introduce missing element (subject or verb).
  3. Connect to preceding or following sentence.

Sentence fragments with missing elements are corrected by making sure that each has both an adequate subject and a complete verb:

I had never eaten so much. [Note: I is the subject]

I was nervous.  Or   Being nervous, I spoke far too quickly. [Note: I is the subject]

The chips and beer tasted great. [Note: tasted is the verb]

Sometimes a sentence fragment can be corrected by combining it with the preceding or following sentences you have written. 

Being nervous. I spoke far too quickly. [Note: ‘being nervous’ is a sentence fragment]

You need to correct the fragment by changing the period to a comma, and attaching the fragment to the simple sentence:

Being nervous, I spoke far too quickly. [Note: correct sentence]

Sentence fragments increasingly are used in writing for social media, the internet, newspapers, and other kinds of non-academic writing. Despite their popularity, they remain grammatically incorrect and inappropriate for academic and other kinds of formal writing.


Run-On Sentences and Comma Splices

An independent clause has a subject and a verb and can stand alone as a simple sentence. By identifying independent clauses you can avoid two of the most common errors in student writing, known as run-on sentences and comma splices.

Run-On Sentences:

I enjoyed the anthology very much the stories still remain in my mind.

Let's analyze the subject and verbs:

I enjoyed the anthology very much the stories still remain in my mind. (Enjoyed and remain are verbs and I and stories are subjects.)

It becomes clear that the above contains two simple sentences or two independent clauses, each with its own subject-verb. It is a run-on sentence because it is written as if it were only one sentence with no punctuation to show the reader where the first clause ends and the second begins.

Comma Splices:

I enjoyed the anthology very much, the stories still remain in my mind.

A comma has been used instead of a semi-colon to combine the two independent clauses. Commas have many uses; this is not one of them.

Correcting Run-On Sentences and Comma Splices.

There are a few choices to correct sentence structure in this example:

  1. Insert a period before the second independent clause to make two simple sentences.

    1. I enjoyed the anthology very much. The stories still remain in my mind.

  2. Use a semi-colon to join the two clauses and make a compound sentence.

    1. I enjoyed the anthology very much; the stories still remain in my mind.

    2. I enjoyed the anthology very much; consequently, the stories still remain in my mind.

  3. Use a coordinating conjunction to join the two clauses and make a compound sentence.
    1. I enjoyed the anthology very much, so the stories still remain in my mind.