Adapted from http://writing.eng.vt.edu/exercises/

The sentence is the fundamental unit of expression in professional writing. To maintain credibility as a professional, you have to know what constitutes a sentence.

In this exercise, identify whether each of the highlighted word groups is a sentence, fragment, or run-on. Note that a run-on is a specific grammatical term referring not to a long sentence, but to a group of words containing two or more independent clauses that are incorrectly joined.