Complete Sentences

In order to successfully craft sentences, one must first understand the core elements of complete English sentences: subjects, objects, predicates, and modifiers. The most important of these are subjects and predicates: in order for a sentence to be "complete," it must contain an action and someone (or something) doing it. The action is the predicate, and the person (or thing) doing it is the subject.

An incomplete sentence is called a fragment. Compare and contrast the sentences below:

1. I like pizza. Because it tastes delicious.
2. I like pizza because it tastes delicious.

Of the two examples above, the first contains a fragment: "Because it tastes delicious" is a fragment, or an incomplete thought. It has an "action" (tasting delicious) but no subject. 

The second example is correct; it has all the necessary components of a full sentence—a subject and a predicate.

It is important to understand that there are many gray areas of definition and usage when it comes to English-language sentence construction. For the purposes of understanding, we will start with basic ideas and simple examples. When you have a strong grasp of these, you will feel more able to handle the gray areas.

Subjects

The subject of a sentence is a noun or pronoun (and its article, if it has one). In active-voice sentences, it is the noun or pronoun performing the action in the sentence. See the italicized subjects in the examples below:

1. The boy crossed the street.
2. She works in the city.
3. Mark is a good athlete.

In example 1, the subject, "the boy," is both a noun and its article. In example 2, the subject is a pronoun. In example 3, the subject is a noun (no article).

Predicates

The predicate explains the action of the sentence. The simple predicate refers to just the verb or verb phrase, linked to the subject, which tells what action is being performed by that subject. In the examples above, "crossed," "works," and "is" are all simple predicates.

There are more complex definitions of "predicate." Sometimes "predicate" can simply mean "everything except the subject." But just remember: the simple predicate is the action (verb or verb phrase) of a sentence.

In the examples below, the predicates are italicized:

• The house is green. 
• She seems angry.
• The burden became excessive.

Objects

The object of a sentence is the noun or pronoun which is being acted upon, or at which the action is directed. There are two types of objects: direct objects and indirect objects. 

Direct Object

The direct object is the object which is being acted upon in the sentence. See the italicized direct objects in the examples below:

• Johnny throws the ball.
• Jill cuts the cake.
• Bill rides the bike. 

Indirect Object

The indirect object answers the questions “to whom/what?”or “for whom/what?” in a sentence. It is not acted upon. See the italicized indirect objects in the examples below:

• Johnny throws the ball to me.
• Jill cuts the cake for her friends.
• Bill rides the bike to school.

No Object

Some sentences do not need an object and consist of only a subject and a verb predicate. For example:

• Mary smiled.
• Fred sneezed.

This can happen because some verbs (like the ones above) don't require an object. When a verb doesn't need an object, it is called an intransitive verb. (We'll talk more about this later.)

Modifiers

A modifier is a phrase in a sentence that provides additional information about an element within that sentence. There are three basic kinds of modifying constructions:

• Single-word modifiers (adjectives and adverbs): It was a nice house.
• Modifying phrases (e.g., prepositional, participial, infinitive, and appositive phrases): Barry Goldwater, the junior senator from Arizona, received the Republican nomination in 1964. (appositive phrase)
• Modifying clauses (a clause is any group of words with its own subject and predicate): The only one of the seven dwarfs who does not have a beard is Dopey. (adjective clause)

Compound Elements

In a given sentence, there may be more than one of any of the five core sentence elements. Compound elements can include:

• Compound subject: Mary and Tom went to the dance.
• Compound predicate: He ran to the house and knocked on the door.
• Compound modifier: He rode a small white pony.

Phrases

A phrase is a collection of words that may have nouns or verbals, but it does not have a subject doing a verb. The following are examples of phrases:

• leaving behind the dog
• smashing into a fence
• before the first test
• after the devastation
• between ignorance and intelligence
• broken into thousands of pieces
• because of her glittering smile

In these examples, you will find nouns (dog, fence, test, devastation, ignorance, intelligence, thousands, pieces). You also have some verbals (leaving, smashing), but in no case is the noun functioning as a subject doing a predicate verb. They are all phrases.

Clauses

A clause is a collection of words that has a subject that is actively doing a verb. The following are examples of clauses:

• since she laughs at men
• I despise individuals of low character
• when the saints go marching in
• because she smiled at him

Note that in the examples above, we find either a noun or a pronoun that is a subject (italicized) attached to a verb phrase (also italicized).

Independent and Dependent Clauses

If the clause could stand by itself—that is, form a complete sentence with punctuation—we call it an independent clause. The following are independent clauses:

• I despise individuals of low character
• Helen loves Canadian geese

We could easily turn independent clauses into complete sentences by adding appropriate punctuation marks. We might say, "I despise individuals of low character." Or we might write, "Helen loves Canadian geese!" We call them independent because these types of clauses can stand by themselves, without any extra words attached, and be complete sentences.

By contrast, dependent (also called subordinating) clauses cannot stand on their own. The following are dependent clauses:

• when the saints go marching in
• because she smiled at him

Sentence diagram 1

This diagram shows some of the component parts of a sentence, and demonstrates how they relate to each other.