A complete sentence is a set of words that combines a subject (a main noun) and an action (a main verb) in order to convey a more comprehensive idea. A complete sentence is the basic unit of communication. It describes (1) a thing and (2) what it does. It is important to understand the mechanics involved in forming a complete sentence in order to avoid sentence fragments. Read on for more information about this and examples of different types of sentence fragments.
A sentence fragment is a phrase that does not include a fully-formed idea because it lacks a subject, an action or both. In formal writing, you should avoid sentence fragments because it can appear unprofessional or unpolished.
Some sentence fragments are not complete sentences because they lack a subject.
INCORRECT: Clutching a book to her chest and pointing to the board with a crazy grin on her face. (Notice that there is no main noun in this sentence. Who is clutching the book to her chest? This sentence does not include a subject, so it is a fragment.)
CORRECT: The teacher was clutching a book to her chest and pointing to the board with a crazy grin on her face.
Some phrases lack an action. These are sentence fragments as well because they do not provide both components necessary for a complete sentence.
INCORRECT: The teacher with a book in her hand and eyebrows floating off the top of her head. (Notice here that there is no action to go along with the subject (‘teacher’). What does the teacher do? Since there is no main verb here, this does not convey a complete thought.)
CORRECT: The teacher with a book in her hand and eyebrows floating off the top of her head yelled at her student.
If you have a problem completing a sentence, try rewording it to find out which word is missing. This is a really easy fix to most fragment problems. In the following example, the word order changes to make the sentence more understandable. The missing word ‘lecture’ is the subject of the sentence in the correct version, rather than the action.
INCORRECT: Is going to lecture.
CORRECT: The teacher is giving a lecture.