Reading Writing Center | Microlab 4

Microlab 4 – Complete Sentences

There’s nothing more important to learning English than understanding sentences! Writers need to know the difference between complete sentences (which express complete thoughts), and sentence fragments (which do not). Being able to recognize and write complete sentences is one of the most important skills in writing. This microlab will help you:

  • Understand the definition of complete sentences
  • Recognize sentence fragments
  • Repair sentence fragments

Review of Complete Sentences

Recognizing a Sentence

A complete sentence must always have a subject and a predicate and express at least one complete thought. [White clouds] [dotted the horizon] (subject ) + (predicate) = sentence

I. Subjects:

A sentence must have a subject. Subjects name people, places, things, ideas, and activities. Most subjects do something in a sentence or describe an action. They are always nouns, but may include modifiers to describe or enhance the noun. Sample Subjects:

Mr. Johnson, my favorite teacher, painted the house yellow.
Far beneath us lay the Fiji Islands
Puzzles fascinate Sally 
On July 4th, freedom is celebrated. 
Woodworking appealed to Jill. 
It is orange and red. 

A sentence without a subject is considered a fragment:

Incorrect:  Blinded Mike.		Correct:  The headlights blinded Mike. 
		(predicate)			(subject)             (predicate)	

Incorrect:  Was able to run ten miles.		Correct:  Carol was able to run ten miles. 
		(predicate)				(subject)	(predicate)

Incorrect:  Couldn’t wake up		Correct:  The twins couldn’t make up. 
		(predicate)			(subject)	(predicate)

II. Predicates:

A sentence must have a predicate. Predicates describe what the subject does or is. It is typically a verb and then anything modifying that verb. Sample Predicates (verbs italicized):

Jennifer tickled the cow’s ear. 	
The fan spun dizzily overhead. 
Rumors spread quickly.
Ted is allergic to ink. 
The moon was high in the sky. 

III. Complete thoughts:

Sentences must express a complete thought:

Incorrect:  Because I was in a hurry. (Thought-fragment)     
Correct:  Because I was in a hurry, I forgot my keys. (Complete thought)

These phrases contain a noun and a verb, but are not complete sentences because they cannot stand alone as a complete idea:

Incorrect:  When I went home. (Incomplete thought)         
Correct:  When I went home, I called Nikki. (Complete sentence) 

Incorrect:  That I want. (Incomplete thought)
Correct:  She bought the shoes that I want. (Complete Sentence) 

IV. Verb form:

Some sentences have both a noun and a verb, but the verb is in the wrong form. When this is the case, it is typically in the gerund form (walking is the gerund form of to walk for example), which simply modifies the noun, not describing an action. “Jack waving,” for example, is a sentence fragment. Waving cannot stand alone as a verb. In this instance, waving is describing a characteristic of Jack, not the action that he is performing (and is, technically, part of the subject). “Jack is waving,” is a complete sentence because the verb is formed correctly.

Incorrect:  The lawn being wet. (Incorrectly formed verb)
Correct:  The lawn is wet. (Correctly formed verb)

Incorrect:  Maria singing for hours. (Incorrectly formed verb)
Correct:  Maria singing for hours was annoying. (Correctly formed verb--singing modifies Maria
 and is not the main verb of the sentence)

V. Implied subjects:

An exception to the rule of having a subject of a sentence is when there is an implied subject, meaning that a subject is not present, but it is implied. This is usually a command, where the subject “you” is implied:

Implied				Including Subject
Correct:  Go take out the trash!	 (You go take out the trash!)
Correct:  Don’t go!		   	 (You don’t go!)

VI. Recognizing sentence fragments:

Recognizing sentence fragments (or incomplete sentences) is important!

The cat
(subject) 	+	 (predicate)			= fragment

			ran away from me
(subject) 	+	 (predicate)			= fragment

The headlights 		blinded Mike. 	
(subject) 	+	 (predicate)			= sentence 

The car			running smoothly		
(subject) 	+        (incorrectly formed verb)		= fragment

Since I left
(incomplete thought)					= fragment

Change his diaper.
(command—implied subject, “you”)			=sentence			

Since I left, the car has been running smoothly.					
(subject)	+	(predicate)			=sentence

Key Points to Remember:

  1. Every sentence must have a subject. To identify fragments, find who or what the sentence is talking about.
  2. A correct sentence needs a predicate, which defines what a subject is doing.
  3. Although fragments may contain a noun and a verb, they do not express a complete thought.
  4. The verb must be formed correctly for a group of words to become a sentence.
  5. Some complete sentences may have implied subjects.