“It’s the basis of ordinary etiquette / to be sure of your subject and your predicate.” This song lyric from a children’s play about acceptable grammar is certainly true; however, not many people can point out the predicate in a sentence (even if they are sure of the subject). In reality, determining the predicate of a sentence isn’t that difficult. It is simply a matter of knowing how sentences function, beginning with the parts of speech and the way that they relate to each other. If you have trouble distinguishing your subject—or anything else, for that matter—from your predicate, read on for some helpful tips about what predicates are and how they work.
Simply put, the predicate of a sentence is the part that modifies the subject in some way. Because the subject is the person, place, or thing that a sentence is about, the predicate must contain a verb explaining what the subject does. Look at some of the shorter sentences in the English language:
These sentences are very simple examples of what predicates are, since the predicate is expressed entirely by one word. Predicates may also be whole phrases.
“I am” is often described as the shortest sentence in the English language, but this is not exactly true. “I am” may contain a subject and a verb, but it doesn’t explain what “I am;” an additional piece of the phrase is necessary to complement the verb.
Whatever you add to “I am” technically forms the predicate of the sentence. Take, for example, the phrase “I am playing guitar all day.” The subject of this sentence does not change—“I” remains the focus of the sentence; the person about whom the sentence is written; the noun around whom the action centers. What has changed is that the weak to-be verb “am” is enhanced by the presence of additional words explaining what and how.
“I am playing.” Playing what? “I am playing guitar.” How are you playing guitar? “I am playing guitar all day.”
Now you see? The verb phrase “am,” the verb phrase “am playing guitar,” and the adverbial “all day” fully express what the subject “I” is trying to say. The sentence now has both a subject and a predicate.
Now that you know “I am” is not technically a full sentence, you’ll probably be quick to notice other examples that seem like full sentences but lack a predicate, such as “I can” and “I will.” What might confuse you is the sentence that seems to lack a subject. As surprising as it may sound, the shortest complete sentence in the English language is the imperative, “Go!” How can this be? After all, “go” is a verb seemingly without a subject or a predicate.
There are two things you’ll need to understand before this example will make sense.