Elements of Sentence Construction

Subjects and Predicates

Parts of speech have specific tasks to perform when they are put together in a sentence.
A noun or pronoun functions as the sentence subject when it is paired with a verb functioning as the sentence predicate.
Every sentence has a subject and predicate.
A subject can be a noun or pronoun that is partnered with an action verb.
        Example:
                   
Sometimes a verb will express being or existence instead of action.
        Example:
                         
Sometimes we use sentences in which a subject is not actually stated, but is, nevertheless, understood in the meaning.
        Example:
                               
                A sentence like this gives an order or a request to someone.
                       
Because we use such statements when we are talking directly to someone, we omit the word you.  It is understood in the sentence.  Therefore, in statements like this one, we say the subject is  
                                                    you (understood).
This kind of sentence is an imperative sentence.
    
A predicate is a verb that expresses the subject's action or state of being.
            Example:
                            
Sometimes the predicate will be composed of two or three verbs that fit together - the main verb preceded by one or more auxiliary (helping) verbs.
                           
IMPORTANT NOTE:  To be a predicate, a verb that ends in -ing must ALWAYS have a helping verb with it.  An -ing verb WITHOUT a helping verb cannot be a predicate in a sentence.
         
A subject and predicate may not always appear together or in the normal order, as the following examples show:
                            
       
                           
  
                           
     

Phrases

A phrase is a group of related words that 
                1. does not express a complete thought
                2.  does not have a subject and predicate pair
One type of phrase is a prepositional phrase.
                  Examples:                         
                             
Another kind of phrase is a verbal phrase. 
                Examples:  
                       
Even though these phrases contain nouns (pronouns) and/or verb forms, none of the nouns/pronouns/verbs are subjects or predicates.  None of them work as a partnership.
Also, these phrases do NOT express complete thoughts.
         

Clauses

Words and phrases can be put together to make clauses.
A clause is a group of related words that contain a subject and predicate.
Note the difference between phrases and clauses in the following examples:
                     
Only one of the clauses is a sentence.
Clause #1 gives a thought or an idea that is COMPLETE, that can stand by itself, independent of other words.
However, clause #2 gives an INCOMPLETE thought or idea, one that cannot stand by itself, one that needs some more words to make it whole.  The word after changes the meaning, making the thought incomplete.  After reading this clause, we are left hanging.  

These two clauses illustrate the two kinds of clauses:
            independent clauses and dependent clauses
An independent clause is a group of words that contains a subject, a predicate, and a complete thought.
A dependent clause is a group of words that contains a subject and a predicate, but does NOT express a complete thought.

Compounding Sentence Elements  

Words, phrases, and clauses may be joined to one another inside a sentence with a conjunction.

The coordinating conjunctions and, but, or, and nor may join subjects, predicates, adjectives, adverbs, prepositional phrases or dependent clauses within a sentence.  This process is called "compounding."

The following examples show the process of compounding

WORDS

         
  

PHRASES
   

DEPENDENT CLAUSES
  

When entire independent clauses (simple sentences) are joined this way, they become compound sentences.

Avoiding Fragments

A complete sentence needs only two elements:
        a subject - predicate unit    AND    a complete thought
In other words, a simple sentence is actually the SAME thing as an independent clause.
Dependent clauses or phrases are called fragments because they are missing one or more parts needed to make a sentence.  
Therefore, they are only pieces or fragments of complete sentences. 
Look at these examples:

           

Avoiding Comma Splices and Fused Sentences

Sometimes two independent clauses (simple sentences) can be joined to form another kind of sentence: the compound sentence.
Two major errors can occur when constructing compound sentences.
Error #1: The Comma Splice
Writers make this error when they try to separate the two independent clauses in a compound sentence with a comma alone.
A comma is not a strong enough punctuation mark to separate the two independent clauses by itself; thus, using it causes the clauses to be spliced together.
Example of a comma splice:
               
This sentence can be repaired in three ways:
    1.  by adding an appropriate coordinating conjunction   
           
    2.  by changing the comma to a semicolon
               
    3.  by changing the punctuation and adding an appropriate conjunctive adverb
            
Error #2: The Fused Sentence
Writers make this error by joining two independent clauses into a compound sentence without using any punctuation between them.
No punctuation between the two independent clauses causes them to "fuse" into an INCORRECT compound sentence.
Example of a fused sentence:
            
This sentence is also repaired in three ways:
    1.  by adding a comma and an appropriate coordinating conjunction
           
    2.  by placing a semicolon between the two clauses
           
    3.  by adding the needed punctuation and an appropriate conjunctive adverb
           

Another way to repair a comma splice or fused sentence is to make each independent clause into a simple sentence.