C. Subjects and Predicates
What are Subjects and Predicates?
Once you are comfortable picking out the subject and the verb, it can be helpful to think of sentences in larger parts. Every sentence has a subject and a predicate. The subject of a sentence is the noun, pronoun, phrase or clause the sentence is about, and the predicate is the rest of the sentence after the subject, which tells us more about what the subject does or is and, therefore, must contain a verb explaining what the subject does (and can also include modifiers). The predicate is basically everything in the sentence that is not the subject.
In the following sentences, the subject is in bold and the predicate is underlined:
Example 1
- Einstein’s general theory of relativity has been subjected to many tests of validity over the years.
- In a secure landfill, the soil on top and the cover block storm water intrusion into the landfill.
- This is called a compound subject because there are two subjects in this sentence: soil and cover.
- Notice that the introductory phrase, “In a secure landfill,” is not a part of the subject or the predicate.
- The pressure is maintained at about 2250 pounds per square inch then lowered to form steam at about 600 pounds per square inch.
- This is called a compound predicate because there are two predicates in this sentence: “is maintained at about 2250 pounds per square inch” and “lowered to form steam at about 600 pounds per square inch.”
- Surrounding the secure landfill on all sides are impermeable barrier walls.
- This sentence has an inverted sentence pattern. In an inverted sentence, the predicate comes before the subject. You won’t run into this sentence structure very often, as it is pretty rare.
A predicate will always include the verb, and it may also contain a direct object and an indirect object. It can help to note that the predicate usually begins with a verb.
Exercise 1
Direct Object
A direct object—a noun, pronoun, phrase, or clause acting as a noun—takes the action of the main verb (e.g., the verb is happening to the object). A direct object can be identified by putting what?, which?, or whom? in its place. As above, the subject is in bold, and the predicate is underlined, but the direct object is italicized to help you see how the parts work together.
Example 2
- The housing assembly of a mechanical pencil contains the mechanical workings of the pencil.
- The main verb of this sentence is “contains,” so the direct object “workings” answers the question “The housing assembly…contains …what?”
- It may help to note that the phrases “of a mechanical pencil” and “of the pencil” are prepositional phrases, and are therefore not essential to the grammar of the sentence. Try reading the sentence without these phrases to better understand how the subject, predicate, and direct object work together.
- Lavoisier used curved glass discs fastened together at their rims, with wine filling the space between, to focus the sun’s rays to attain temp