2.1: Components of a sentence
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A complete sentence consists of a subject and a predicate. The subject is the word or group of words that names the person, place, thing, or idea that the sentence is about, and the predicate consists of the verb and any words that are necessary to complete its meaning. Both subject and predicate are necessary for the sentence to express a complete thought. In a way, every sentence can be compared to a story. Like a story, a sentence must be about someone or something, and that person or thing must have something said about it. In grammatical terms, a complete sentence is an independent clause, which is a group of words that contains a subject and a predicate and can stand on its own as a complete thought.
Example: I could not play in the basketball game.
In this sentence the subject is I, and the rest of the sentence is the predicate. Now consider this clause:
Example: Because I sprained my ankle.
Here also the subject is I, and there is a predicate, sprained my ankle, but this clause is dependent (or subordinate), which means that in order to express its meaning completely it must be joined to an independent clause, as follows:
Example: Because I sprained my ankle, I could not play in the basketball game.
As this example illustrates, a dependent (or subordinate) clause cannot stand on its own. It must be joined to an independent clause to make its meaning clear. All complete sentences must contain at least one independent clause.
Compound Subjects
A sentence may have more than one person, place, thing, or idea as the subject. When this occurs, the sentence has a compound subject.
Example: The students and teachers left the building when the fire alarm sounded.
In this example, the phrase students and teachers is a compound subject.
Prepositional Phrases
A phrase is a group of words that cannot function as a clause because it lacks either a subject, a predicate, or both. A prepositional phrase is a modifying unit that indicates a relationship of some kind (often a relationship of space or time) between the object of the preposition and another word.
Example: The book was found underneath the couch.
In this example, underneath the couch is a prepositional phrase. The object of the preposition is couch, and the preposition underneath indicates the relationship between the subject of the sentence (book) and the couch.
Common prepositions include in, on, of, under, near, by, with, and about.
Participial Phrases
Just as prepositional phrases are built on prepositions, participial phrases are built on either the past or present participle of a verb. They are used as modifiers and usually describe nouns. The participles commonly used in English are the present participle (the –ing form of verbs) and the past participle (the –ed form of regular verbs). Thus, walking and walked are the present and past participles of the verb to walk. A participial phrase consists of the verb participle and any modifiers that go with it.
Example: walking over rocky ground.
In this example, walking is the participle and over rocky ground (a prepositional phrase) completes the participial phrase.
Since many participial phrases contain the participle of an action verb, students sometimes confuse a participial phrase with the main verb of a sentence. Look closely, though, and you will see that the action word in a participial phrase is never a complete verb. It is usually only a past or present participle that lacks the helping verb it would need to form a predicate.
Example: A young man staring at his cell phone bumped into me.
The subject of this sentence is A young man, and there may seem to be two predicates, staring at his cellphone and bumped into me. One of these, however, is only a participial phrase. How can you tell which one? If you remove the first of these two phrases, you get A young man bumped into me. This is clearly a complete sentence with a verb, bumped, in the past tense. However, if you remove the second phrase, you get A young man staring at his cell phone. Is this a complete sentence? Compare it with this:
A young man was staring at his cellphone.
Only when we add was do we have a complete sentence. Why? Because staring cannot function as a verb without the helping verb was or is. So in our original sentence staring at his cell phone is a participial phrase used to describe the young man, and the predicate is bumped into me.
Exercise
Read the following sentences. Underline the subjects, and circle the prepositional phrases:
1. The gym is open until nine o’clock tonight.
2. We went to the store to get some ice.
3. The student with the most extra credit will win a homework pass.
4. Maya and Tia found an abandoned cat by the side of the road.
5. The driver of that pickup truck skidded on the ice.
6. Anita won the race with time to spare.
7. The people who work for that company were surprised about the merger.
8. Working in haste means that you are more likely to make mistakes.
9. The soundtrack has over sixty songs in languages from around the world.
10. His latest invention does not work, but it has inspired the rest of us.