Components of a Sentence
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.
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:
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:
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.