Sentence Boundaries

Clear sentence structure depends on establishing where a sentence ends and the next one begins. Every sentence must have an independent clause. The clause is called independent when it includes a subject, a verb, and other words which express a complete thought together. Many sentences may contain two independent clauses and one or more dependent clauses joined with appropriate conjunctions and/or punctuation.

I. Run-Ons

Combining two or more sentences without appropriate conjunctions and/or punctuation results in a run-on sentence.

Study these examples.

  1. My dad came to pick me up this morning my school bag is still in the back of your car I was wondering if maybe you could drop it off on your way home. (incorrect)
  2. My dad came to pick me up this morning, but my school bag is still in the back of your car, so I was wondering if maybe you could drop it off on your way home. (correct)

The three sentences are joined without appropriate conjunctions and/or punctuation.

  1. My dad came to pick me up this morning
  2. my school bag is still in the back of your car
  3. I was wondering if maybe you could drop it off on your way home.

II. Comma Splices

Combining two or more sentences with commas results in comma-spliced sentences.

Study these examples.

  1. Topic sentences are important, they introduce the controlling idea of a paragraph. (incorrect)
  2. Topic sentences are important, for they introduce the controlling idea of a paragraph. (correct)

Correct the following.

  1. It was close to 7 o’clock, I began to prepare dinner.
  2. My grandparents have a small field they grow vegetables.
  3. It was mid-June when we went to Florida we spent the whole summer there.
  4. I will learn, how to enrich and change the lives of those, I come into contact with.
  5. I decided to take a class outside of my major, I ended up taking an introductory physics class.

III. Fragments 

When an incomplete sentence is treated as if it were a complete sentence, it is a fragment error.

Study these examples.

  1. The painting won a prize because was so original. (incorrect)
  2. The painting won a prize because it was so original. (correct)

The subject "it" is omitted.

  1. After they finished practice. (incorrect)
  2. After they finished practice, they drove home. (correct)

This is a dependent clause because it begins with "after." For the sentence to be complete, the dependent clause should be connected to the independent clause.

Correct the following:

  1. Or that they both try different ways to save the economy and health care.
  2. A war that I feel has lost its purpose, control, and support.
  3. A man who knows and understands the needs that the majority of citizens in this country express.
  4. Facts such as who has the ability to make change in this country and which candidate has a plan to get us out of this economic downfall.
  5. Although he arrived late for his flight.

References

Explanations and some examples are adapted with modifications from the following resources:

Ferris, D. (2014). Language power: Tutorials for writers. Boston: Bedford/St Martin's.